ALBERT

Description: 〈p〉Publication date: 10 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 296〈/p〉 〈p〉Author(s): Saheed Bukola, Stephen E. Creager〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Transmission rates for protons and deuterons across single-layer graphene embedded in Nafion | graphene | Nafion sandwich structures are measured as a function of temperature in electrochemical hydrogen pump cells. Rates of ion transmission through graphene are obtained in the form of area-normalized ion-transfer resistances, and are interpreted in terms of ion-exchange current densities and standard heterogeneous ion-transfer rate constants. An encounter pre-equilibrium model for the ion-transfer step is then used to provide rate constants for the fundamental microscopic step of ion (proton or deuteron) transmission across graphene. Application of this rate model to interpret variable-temperature data on proton and deuteron transmission rates provides values for the activation energy and pre-exponential factor for the fundamental ion transmission step across graphene. Activation energies obtained from the Arrhenius plots for proton and deuteron transmission are as follows; for proton, E〈sub〉act〈/sub〉 = 48 ± 2 kJ/mole (0.50 ± 0.02 eV) and for deuteron, E〈sub〉act〈/sub〉 = 53 ± 5 kJ/mole (0.55 ± 0.05 eV). The difference between these two values of approximately 5 kJ/mole is in good agreement with the expected difference in vibrational zero-point energies for O〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H and O-D bonds, albeit with some uncertainty given the uncertainties in the activation energy values. Pre-exponential frequency factor values of 8.3 ± 0.4 × 10〈sup〉13〈/sup〉 s〈sup〉−1〈/sup〉 and is 4.7 ± 0.5 × 10〈sup〉13〈/sup〉 s〈sup〉−1〈/sup〉 were obtained for proton and deuteron transmission respectively across graphene. These pre-factor values are both quite large, on the order of the values predicted from the Eyring – Polanyi equation with a transmission coefficient near one. The ratio of 1.8 for the rate pre-factors (H/D) is in reasonable agreement with the value of 1.3 for the ratio of bond vibrational frequencies for O〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H and O-D stretching, respectively. Taken together, these data support a model in which proton and deuteron transmission across graphene are largely adiabatic processes for which the differences in transmission rate at room temperature are due largely to differences in activation energies.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 295〈/p〉 〈p〉Author(s): Kaili Jin, Man Zhou, Hong Zhao, Shixiong Zhai, Fengyan Ge, Yaping Zhao, Zaisheng Cai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉With the large theoretical capacity and environmental benignity, copper sulfide (CuS) becomes a prospective candidate electrode material for supercapacitors. In this work, electroconductive mesoporous carbonized clothes (Cc) was obtained by carbonizing the waste cotton fabrics. Then the CuS was galvanostatic electrodeposited on 〈em〉Cc〈/em〉 to prepare the binder-free 〈em〉g〈/em〉-CuS/Cc electrode. In the galvanostatic electrodeposition process, CuS grew along the crystal surface to form regular nanosheets, and a part of Cu〈sup〉2+〈/sup〉 were reduced to Cu〈sup〉1.1+〈/sup〉. In addition, on account of the synergistic effect of electrochemical double layer capacitance with pseudocapacitance and the high specific surface area (450.76 m〈sup〉2〈/sup〉 g〈sup〉−1〈/sup〉), the 〈em〉g〈/em〉-CuS/Cc composite displayed not only outstanding areal specific capacitance (4676 mF cm〈sup〉−2〈/sup〉 at 2 mA cm〈sup〉−2〈/sup〉) but also excellent cycling performance (89.8% retention after 10000 cycles). Meanwhile, the symmetrical flexible supercapacitor (SC) based on 〈em〉g〈/em〉-CuS/Cc electrodes with PVA-KOH gel electrolyte (〈em〉g〈/em〉-CuS/Cc-SC) accomplished a high specific capacitance of 1333 mF cm〈sup〉−2〈/sup〉 at 2 mA cm〈sup〉−2〈/sup〉 as well as ultrahigh energy density of 0.96 Wh cm〈sup〉−2〈/sup〉 at the power density of 4.36 W cm〈sup〉−2〈/sup〉. Therefore, 〈em〉g〈/em〉-CuS/Cc shows a great potential for applications in the next generation of flexible energy storage devices.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618324447-fx1.jpg" width="384" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 295〈/p〉 〈p〉Author(s): Kang Li, Zhanwei Xu, Xuetao Shen, Kai Yao, Jianshe Zhao, Ronglan Zhang, Jun Zhang, Li Wang, Jianfeng Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Commercial lithium/thionyl chloride (Li/SOCl〈sub〉2〈/sub〉) batteries cannot meet the 3.15 V platform required for most instruments. A 〈em〉hovenia acerba〈/em〉-like assembly constructed with cobalt tetrapyridinoporphyrazine of thickness of 5–15 nm is anchored on acid-functionalized multi-walled carbon nanotubes (CoTAP/MWCNTs), which were prepared using an 〈em〉in situ〈/em〉 solid synthesis process. The discharge time of Li/SOCl〈sub〉2〈/sub〉 batteries with a voltage greater than 3.15 V catalyzed by CoTAP/MWCNTs is found to be 11 min longer than batteries without catalysts and 4 min longer than those catalyzed by CoTAP alone. The energy of Li/SOCl〈sub〉2〈/sub〉 batteries with a voltage greater than 3.15 V catalyzed by CoTAP/MWCNTs is discovered to be 11.44-times higher than batteries with AF-MWCNTs and 6.17-times higher than those catalyzed by bulk CoTAP. This is due to the fact that more CoTAP ultrafine nanoparticulates are anchored on the AF-MWCNTs. These nanoparticulates provide more active sites for the catalytic reaction of SOCl〈sub〉2〈/sub〉. The assemblies are shown to have an adsorption-coordination effect on Li ions and to delay the deposition of lithium chloride passive films enhancing battery voltage platforms.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉A 〈em〉hovenia acerba〈/em〉-like assembly constructed with cobalt tetrapyridinoporphyrazine of thickness of 5–15 nm is anchored on acid-functionalized multi-walled carbon nanotubes (CoTAP/MWCNTs), which were prepared using an 〈em〉in situ〈/em〉 solid synthesis process. The discharge time of Li/SOCl〈sub〉2〈/sub〉 batteries with a voltage greater than 3.15 V catalyzed by CoTAP/MWCNTs is found to be 11 min longer than batteries without catalysts and 4 min longer than those catalyzed by CoTAP alone.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618324319-fx1.jpg" width="270" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 295〈/p〉 〈p〉Author(s): Shuxing Wu, Hengzhi Guo, Kwan San Hui, Kwun Nam Hui〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Rational electrode architectural design, favorable electrode composition, and versatile synthesis approach play a significant role in developing advanced electrodes for high-performance supercapacitor. In this work, we report a facile approach for fabricating 1D hierarchical CuO@Co〈sub〉〈em〉x〈/em〉〈/sub〉Ni〈sub〉〈em〉1−x〈/em〉〈/sub〉(OH)〈sub〉2〈/sub〉 nanowire arrays grown on 3D highly conductive copper foam. The optimized CuO@Co〈sub〉0.2〈/sub〉Ni〈sub〉0.8〈/sub〉(OH)〈sub〉2〈/sub〉 electrode delivers an ultrahigh specific capacity of 374.7 mAh g〈sup〉−1〈/sup〉 at 2 A g〈sup〉−1〈/sup〉 with exceptional rate capability (301.7 mAh g〈sup〉−1〈/sup〉 at 50 A g〈sup〉−1〈/sup〉) and remarkable cycling stability (95.9% after 10 000 cycles at 50 A g〈sup〉−1〈/sup〉). A flexible asymmetric solid-state supercapacitor (ASC) is fabricated using the optimized CuO@Co〈sub〉0.2〈/sub〉Ni〈sub〉0.8〈/sub〉(OH)〈sub〉2〈/sub〉 as the positive electrode, activated carbon-coated nickel foam as the negative electrode, and polyvinyl alcohol/KOH gel as electrolyte. The flexible ASC operating with a potential window of 0–1.6 V delivers an energy density of 46.5 Wh kg〈sup〉−1〈/sup〉 with a power density of 526.9 W kg〈sup〉−1〈/sup〉. The ASC also exhibits excellent cycling stability with a capacity retention of 84.3% after 10 000 cycles at a current density of 7 A g〈sup〉−1〈/sup〉.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618324459-fx1.jpg" width="325" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 295〈/p〉 〈p〉Author(s): Krishnan Shanmugam Anuratha, Hsiao-Shan Peng, Yaoming Xiao, Tzu-Sen Su, Tzu-Chien Wei, Jeng-Yu Lin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this current work, a bifunctional TiO〈sub〉2〈/sub〉 thin film with reduced pin-hole effect and enhanced light trapping capability was successfully fabricated by using a facile galvanostatic anodic deposition route in the presence of Brij-58 soft template (ST). The surface morphology of electrodeposited TiO〈sub〉2〈/sub〉 thin film using ST confirmed the formation of nano-sized TiO〈sub〉2〈/sub〉 particles with improved porous nature than that of TiO〈sub〉2〈/sub〉 thin film electrodeposited in the absence of ST. Compared with the conventional scaffold porous layer (PL) fabricated from commercial mesoporous TiO〈sub〉2〈/sub〉 composed of ∼30 nm nanoparticles, the electrodeposited TiO〈sub〉2〈/sub〉 film using ST demonstrated the reduced pinhole effect and improved light trapping feature. Owing to the bifunctional behavior of electrodeposited TiO〈sub〉2〈/sub〉 using ST, the cell efficiency of the perovskite solar cell was achieved up to 17.06% which was ca.10% higher than those with commercial TiO〈sub〉2〈/sub〉 nanoparticles.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 296〈/p〉 〈p〉Author(s): Kadir Tuna, Arnd Kilian, Thorsten Ressler〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electroless plating of tin layers with thicknesses of more than 3 μm is becoming an important process in the production of circuit boards and semiconductor. Phosphonates constitute promising complexing agents for autocatalytic tin electrolytes. However, detailed time-resolved investigations or electrochemical impedance spectroscopy (EIS) measurements of tin deposition in this system are lacking. Here, deposition of tin was investigated by electrochemical quartz microbalance (EQCM) and electrochemical impedance spectroscopy. EQCM investigations showed a strong drop in deposition rate within the first ten minutes. Bath parameters had a significant effect on the drop of deposition rate. The results indicated an inhibitive pyrophosphate adsorption on the tin electrode surface which caused the observed drop of deposition rate. Impedance measurements confirmed this assumption. The equivalent circuit applied for the analysis of EIS data, included an increasing adsorbate resistance Rp, which can be related to the thickness of an adsorbed permeable pyrophosphate layer. Impedance measurements at selected frequencies revealed a linear relation between deposition rate and conductance 1/Rp. Subsequently, gluconate substituting for pyrophosphate was tested as complexing agent. Combined EQCM and EIS measurements during deposition using a gluconate containing electrolyte showed a stable rate with an invariant conductance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 295〈/p〉 〈p〉Author(s): Tao Liu, Xiaolin Sun, Shimei Sun, Quanhai Niu, Hui Liu, Wei Song, Fengting Cao, Xichao Li, Takeo Ohsaka, Jianfei Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lithium-sulfur batteries were investigated as promising next-generation energy storage devices owing to their high capacity in comparison to conventional lithium-ion batteries. Nevertheless, the serious shuttle effect and sluggish redox kinetics originated from dissolution of polysulfides and insulating property of sulfur and lithium sulfide, restricted their practical applications. To overcome these stubborn problems, a robust and environment-friendly biomass carbon fiber interlayer anchored with uniformly-distributed SiO〈sub〉2〈/sub〉 nanoparticles was demonstrated. Benefiting from the excellent conductivity of carbon fiber, together with the stable chemical adsorption of SiO〈sub〉2〈/sub〉 for soluble polysulfides, this low-cost and lightweight interlayer could not only remarkably enhance sulfur utilization, but also efficiently capture the polysulfides by chemical entrapment strategies. With this biomass carbon fiber@SiO〈sub〉2〈/sub〉 interlayer, the batteries delivered a high reversible capacity of 1352.8 mAh g〈sup〉−1〈/sup〉 at 0.1 C and enhanced capacity of 618.4 mAh g〈sup〉−1〈/sup〉 after 500 cycles at 1.0 C. Even up to 4.2 mg cm〈sup〉−2〈/sup〉 sulfur loading, high cycling stability was also achieved by this interlayer. We believe this robust and low-cost interlayer has a great potential for practical applications of Li–S batteries.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 295〈/p〉 〈p〉Author(s): Lei Lu, Xinyan Jiao, Jiawei Fan, Wu Lei, Yu Ouyang, Xifeng Xia, Zhixin Xue, Qingli Hao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Oxygen reduction reaction (ORR) and Lithium storage both play the key roles in energy conversion and storage devices. Here, we report a honeycomb-like nitrogen-doped carbon derived from enteromorpha algae (N-EA), using a one-step pyrolysis process at only 600 °C to simultaneously achieve doping, carbonization and activation. After anchoring CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 on N-EA, CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/N-EA, not only inherits the high surface area, porous structure, active nitrogen species from N-EA, but also benefits from the active sites and high theoretical specific capacity of Li storage from CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉. The synergistic effect makes CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/N-EA an alternative catalyst to commercial Pt/C for ORR with superior activity and stability. Moreover, CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/N-EA exhibits a remarkable cycle performance with a 100% capacity retention (∼900 mAh g〈sup〉−1〈/sup〉) after 500 cycles at 0.5 A g〈sup〉−1〈/sup〉. Green preparation, waste utilization, good ORR performance and Li storage property of CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/N-EA could make it a promising candidate for fuel cells and LIBs.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 295〈/p〉 〈p〉Author(s): Pablo A. García-Salaberri, Iryna V. Zenyuk, Gisuk Hwang, Marcos Vera, Adam Z. Weber, Jeff T. Gostick〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Thin porous media are present in multiple electrochemical energy devices, where they provide key transport and structural functions. The prototypical example is gas diffusion layers (GDLs) in polymer-electrolyte fuel cells (PEFCs). While modeling has traditionally been used to explore PEFC operation, this is often accomplished using volume-averaged (VA) formulations, where the intrinsic inhomogeneities of the GDL are smoothed out and the lack of defining a representative elementary volume is an ever-present issue. In this work, the predictions of a single-phase VA PEFC model are compared to those of a pore-scale PEFC model using GDL tomograms as a part of the meshed domain to delineate important aspects that VA models cannot address. The results demonstrate that while VA models equipped with suitable effective properties can provide a good average estimate for overall performance, the lack of accounting for real structures limits their predictive power, especially for durability and degradation behavior where large deviations are found in the spatial distributions. Furthermore, interfacial effects between the GDL and the microporous layer are explored with the pore-scale model to understand the implications of the layered geometry. It is shown that the actual microstructure of the GDL/MPL transition region can significantly affect the fluxes across the sandwich, something that VA models cannot easily consider. Interfacial design is recognized as a key quality control parameter for large-scale MEA manufacturing and assembly.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618320759-fx1.jpg" width="331" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 296〈/p〉 〈p〉Author(s): Jinjun Tian, Yan Xue, Mengmeng Wang, Yuanchao Pei, Hucheng Zhang, Jianji Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉High performances, cost-effectiveness, and facile preparation of electrode materials are of utmost importance for supercapacitors in practical applications. Herein, Ni(HCO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉 nanoparticles (NPs) of low cost and environmental friendliness were embedded into polydopamine-reduced graphene oxide (PDA-RGO) networks via cost-effective hydrothermal route. It is shown the conducting PDA can uniformly distributes and robustly immobilizes Ni(HCO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉 NPs in the nanocomposite while the ionic channels are improved for electrolyte access. Consequently, the as-prepared Ni(HCO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉-PDA-RGO composite offers the high Faradaic capacity of 870 C g〈sup〉−1〈/sup〉 at 0.5 A g〈sup〉−1〈/sup〉 and moderate rate capability. Furthermore, the assembled Ni(HCO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉-PDA-RGO//activated carbon hybrid supercapacitor (HSC) delivers a specific capacity of 192 C g〈sup〉−1〈/sup〉 at 0.5 A g〈sup〉−1〈/sup〉 within operation voltage window of 1.7 V. The maximum energy density of the HSC reaches to 45.3 Wh kg〈sup〉−1〈/sup〉 at a power density of 425 W kg〈sup〉−1〈/sup〉, and the initial specific capacity maintains 90.5% after 3000 successive charge-discharge cycles. The high energy density and good cycleability certify the potential of the ternary Ni(HCO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉-PDA-RGO composite in efficient and long lifetime energy storage systems.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 295〈/p〉 〈p〉Author(s): Libin Zeng, Xinyong Li, Shiying Fan, Zhifan Yin, Mingmei Zhang, Jincheng Mu, Meichun Qin, Tingting Lian, Moses Tadé, Shaomin Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Structure-controlled visible light driven photo-anode with high catalytic performance, plays important roles in environmental pollutants treatment. In this work, a mild hydrothermal assisted anodization approach has been reported to design an integrated self-assembled 3D flower-like MoS〈sub〉2〈/sub〉/1D TiO〈sub〉2〈/sub〉 nanotube arrays (NTAs) hierarchical electrode. The constructed multidimensional electrode not only broadened the absorption spectrum response range but also promoted rapidly electron-hole pairs separation, exhibiting the excellent photoelectron catalytic (PEC) performance and stability in the degradation of target pollutants, which the photocurrent conversion efficiency was 6.5 times higher than that of pure TiO〈sub〉2〈/sub〉. Furtherly, a comprehensive mechanism was proposed to explain the charge transfer on the interface of intimate integration of 3D/1D hybrid nanostructure towards PEC properties in terms of the energy band structures and DFT. Furthermore, the photo-generated active species (〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/rad"〉OH and 〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/rad"〉O〈sub〉2〈/sub〉〈sup〉−〈/sup〉) have been proved by electron paramagnetic resonance spectroscopy and fluorescence probe over the composites. Thus, this work could provide an effective strategy to design multidimensional coupled heterojunction materials toward solar energy conversion for environmental purification.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618323934-fx1.jpg" width="477" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 295〈/p〉 〈p〉Author(s): Valentín Briega-Martos, José Solla-Gullón, Marc T.M. Koper, Enrique Herrero, Juan M. Feliu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The formic acid oxidation reaction has been studied on Pt(111), Pt(100) and Pt nanoparticles with preferential (111) surface structure in 0.1 M HClO〈sub〉4〈/sub〉 in the presence of different concentrations of acetonitrile. An electrocatalytic enhancement towards the formic acid oxidation has been observed under these conditions, and it is proposed that this enhancement is due to two different effects of the adsorbed acetonitrile species: a third-body effect which hinders the formation of CO and a promoting effect of the direct oxidation of formic acid. This promoting effect is structure sensitive. The different enhancement between Pt(111) and Pt(100) indicates that the ratio of free Pt sites and sites occupied by adsorbed acetonitrile is important in order to have the better electrocatalytic activity. On-line mass spectrometry (OLEMS) measurements confirmed the preference for the direct oxidation of formic acid to CO〈sub〉2〈/sub〉, which is almost complete below 0.3 V vs. RHE for Pt(111). Finally, chronoamperometric studies confirmed the lower poisoning rate in the presence of acetonitrile but they also pointed out a competition of formed CO for the Pt sites occupied by acetonitrile species. This work constitutes an example of electrocatalytic enhancement by using an organic molecule for surface modification, which is not as common as using metallic adlayers.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 295〈/p〉 〈p〉Author(s): Yu Li, Bo Lu, Bingkun Guo, Yicheng Song, Junqian Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Partial lithiation strategies for silicon composite electrodes are experimentally investigated in this article. Two types of partial lithiation, i.e. voltage- and capacity-control strategies, are presented. Capacity loss and irreversibility of silicon electrodes are significantly suppressed by either partial lithiation strategy without any complicated modifications or treatments. The capacity of partially lithiated silicon electrodes is even higher than that of fully lithiated one after certain cycles. The images of scanning electron microscope suggest that the mechanical damage generated in partially lithiated electrodes is less than that in fully lithiated one. Furthermore, after dozens of cycles with partial lithiation, capacity decay also slows down in subsequent full charge-discharge cycles. The presented experimental results suggest that the partial lithiation strategy relieves the coupled mechanical-electrochemical degradation and is a promising approach for the long-term use of silicon composite electrodes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 296〈/p〉 〈p〉Author(s): Yu Shi, Haiyan Leng, Liang Wei, Shuanglin Chen, Qian Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The structural characteristics and electrochemical performances of superlattice La〈sub〉5.42〈/sub〉Y〈sub〉18.50〈/sub〉Ni〈sub〉76.08-〈em〉x〈/em〉〈/sub〉Mn〈sub〉〈em〉x〈/em〉〈/sub〉 (〈em〉x〈/em〉 = 0, 2, 4, and 6) metal-hydride electrodes were investigated. La〈sub〉5.42〈/sub〉Y〈sub〉18.50〈/sub〉Ni〈sub〉76.08〈/sub〉 alloy is composed of LaY〈sub〉2〈/sub〉Ni〈sub〉9〈/sub〉, Y〈sub〉2〈/sub〉Ni〈sub〉7〈/sub〉, and La〈sub〉2〈/sub〉Ni〈sub〉7〈/sub〉 phases, while the amount of AB〈sub〉3〈/sub〉-type phase increases due to the increasing substitution amount of Ni by Mn. The mechanisms on the related electrochemical thermodynamics and kinetics were investigated systematically. Compared with La〈sub〉5.42〈/sub〉Y〈sub〉18.50〈/sub〉Ni〈sub〉76.08〈/sub〉 alloy, the maximum discharge capacity of La〈sub〉5.42〈/sub〉Y〈sub〉18.50〈/sub〉Ni〈sub〉70.08〈/sub〉Mn〈sub〉6〈/sub〉 alloy increased from 275.2 mAh g〈sup〉−1〈/sup〉 to 379.6 mAh g〈sup〉−1〈/sup〉 and the discharge capacity after 30 cycles increased from 155.0 mAh g〈sup〉−1〈/sup〉 to 281.1 mAh g〈sup〉−1〈/sup〉, which contribute to the increase of the amount of AB〈sub〉3〈/sub〉-type phase as well as the ameliorated structural stability through the substitution of Mn for Ni.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618324873-egi10F074DV8MS.jpg" width="500" alt="Image" title="Image"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 296〈/p〉 〈p〉Author(s): Na Zhao, Zhaokun Ma, Huaihe Song, Yangen Xie, Man Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Enhancing microbial electrocatalysis through novel anode design is essential to the efficient and stable operation of microbial fuel cells. Carbon fibers modified by the vertical carbon nanotubes/polypyrrole composites can give full play to their advantages, exhibiting excellent conductivity of the vertical carbon nanotubes and good biocompatibility of the polypyrrole. The carbon nanotubes are vertically grown on the carbon fibers by the chemical vapor deposition method, increasing the transfer efficiency of extracellular electron transfer. And then pyrrole is in-situ polymerized on the exterior and interior of the vertical carbon nanotubes, which can not only avoid direct contact between the vertical carbon nanotubes and electricigens to reduce the damage of the vertical carbon nanotubes to electricigens, but also enhance the positive electricity of anode. The modification of the vertical carbon nanotubes/polypyrrole for mesophase pitch carbon fibers anode improves the electricity generation performances of the microbial fuel cells. In this study, the obtained maximum power density is 1876.62 mW m〈sup〉−2〈/sup〉, which is approximately 2.63-fold higher than unmodified carbon fiber brush anode. The results show that the vertical carbon nanotubes/polypyrrole composite anode has demonstrated the high potential for the use of microbial fuel cells.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 296〈/p〉 〈p〉Author(s): Ayman E. Elkholy, Fakiha El-Taib Heakal, Nageh K. Allam〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electrochemical energy storage technologies such as batteries and supercapacitors have a great potential for use in many applications. However, to meet the increasing demand in both the energy and power densities of these devices, further research and development are essential to overcome major obstacles such as cost and durability, which are hindering their commercialization. Herein, we report on the successful deposition of amorphous Mn-Co-Fe ternary hydroxide nanoplatelets directly on Ni foam without the need for any binders. The material was fully characterized using EDS, XRD, FTIR, Raman spectroscopy, XPS and FE-SEM techniques. Upon their use as supercapacitor electrodes, the deposited amorphous mixed hydroxide nanoplatelets demonstrated a maximum specific capacitance of 1200 F/g at a scan rate of 5 mV/s. The asymmetric supercapacitor device showed an energy density of 11.4 Wh/kg with a corresponding power density of 1125 W/kg at a charging current density of 1.5 A/g as calculated from the galvanostatic charging/discharging (GCD) measurements. The cyclic stability of the assembled device was scrutinized via GCD test for 4000 cycles while measuring its electrochemical impedance spectra before and after cycling. The decay in the supercapacitive performance was found to be as low as ∼4% after 4000 GCD cycles, indicating an excellent long-term stability, with the equivalent series resistance (ESR) remained almost constant during those cycles.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618325106-fx1.jpg" width="477" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 296〈/p〉 〈p〉Author(s): Takashi Tsuda, Nobuo Ando, Susumu Nakamura, Yuuta Ishihara, Narumi Hayashi, Naohiko Soma, Takao Gunji, Toyokazu Tanabe, Takeo Ohsaka, Futoshi Matsumoto〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Holing of lithium iron phosphate (LiFePO〈sub〉4〈/sub〉, LFP) cathodes with a pico-second pulsed laser, in which the average hole diameter and hole opening rate were 20–30 μm and 1–2%, respectively, enabled to retain the high-rate discharging performance even in the LFP cathodes composed of the having the LFP layer with the thickness of over 40 μm on an aluminum current collector. The conventional and flat LFP cathode exhibited the degradation of discharge retention at the high-rate discharge because of the low utilization of LFP materials in the case of the thick cathode layer. On the other hand, in the case of “through-holed” and “non-through-holed” LFP cathodes, there can be a more efficient insertion/de-insertion of Li〈sup〉+〈/sup〉 ions to/from the LFP materials through the holes formed in the LFP layer, resulting in retaining the high-rate charging/discharging performance even in thick LFP cathodes. The electrochemical impedance spectroscopy analysis confirmed that the formation of through-holes in the thick LFP layer is significantly effective to improve the high-rate discharging performance as a result of the decreased charge-transfer resistance of the LFP discharge process. The decrease in the charge-transfer resistance results from the increase in the area available in the LFP discharge process because the sidewalls of the holes can also take part in the Li〈sup〉+〈/sup〉 ion transfer during the discharge process.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618324861-fx1.jpg" width="388" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 295〈/p〉 〈p〉Author(s): Haipeng Li, Liancheng Sun, Yan Zhao, Taizhe Tan, Yongguang Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lithium-sulfur (Li-S) batteries represent one of the most promising battery techniques in 21st century. However, the practical implementation of Li-S batteries is impeded by several intractable obstacles including the poor conductivity of sulfur, shuttling behaviour of polysulfides intermediates, and large volume change during sulfur lithiation. Thus, the rational design and morphological control of sulfur cathode paves the way to Li-S batteries practicalizations. Herein, we develop a blackberry-like hollow graphene sphere through spray drying method as a promising sulfur host for Li-S batteries. Attributed to the uniform sulfur distribution, fast reaction kinetics, and excellent sulfur immobilization, the S-HGS composite electrode achieves a highly reversible capacity of 780 mAh g〈sup〉−1〈/sup〉, a great rate capability as well as cyclability without adding additives.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 296〈/p〉 〈p〉Author(s): Jie Ni, Liming Jin, Mingzhe Xue, Junsheng Zheng, Jim P. Zheng, Cunman Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Mesoporous hollow TiO〈sub〉2〈/sub〉 microboxes synthesized by a two-step solvothermal method via CaTiO〈sub〉3〈/sub〉 intermediate were applied as host materials for sulfur cathodes of lithium-sulfur batteries. 3TiO〈sub〉2〈/sub〉/7S composite containing 70 wt% sulfur exhibited the best electrochemical performance among all composites. A high discharge capacity of 924.8 mAh g〈sup〉−1〈/sup〉 was achieved for the 1st cycle and 67.4% of it could be retained after 200 cycles at 0.2 C. Even at a higher C-rate of 1 C, more than 600 mAh g〈sup〉−1〈/sup〉 of discharge capacity could be delivered after 500 cycles. The efficient polysulfide adsorption of TiO〈sub〉2〈/sub〉 microboxes demonstrated by visualized adsorption test and UV–vis measurement as well as the mesoporous hollow feature was responsible for the large discharge capacity, excellent capacity retention and decent rate capability.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618325027-fx1.jpg" width="125" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 295〈/p〉 〈p〉Author(s): Xu Ma, Yi-An Chen, Kefu Zhou, Po-Chang Wu, Chia-Hung Hou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, we report the use of pseudocapacitive RuO〈sub〉2〈/sub〉 in a porous carbon-based substrate as a composite electrode for high-performance capacitive deionization (CDI). RuO〈sub〉2〈/sub〉 was electrodeposited onto inexpensive activated carbon (AC) via cyclic voltammetry to optimize the composite electrode (denoted as RuO〈sub〉2〈/sub〉(20)-AC) fabrication. The electrochemical measurements indicate that the composite electrode with a specific surface area of 576 m〈sup〉2〈/sup〉/g and hydrophilicity yields an improved specific capacitance and good cycling stability. The notably enhanced performance is attributed to the presence of RuO〈sub〉2〈/sub〉, which allows rapid Faradaic charge-transfer reactions as well as pseudocapacitive charge storage. These results confirm that incorporating RuO〈sub〉2〈/sub〉 onto an AC electrode effectively reduces the electrical resistance and enhances the charge efficiency. Furthermore, batch-mode CDI experiments were conducted at 1.2 V in a 5 mM NaCl solution. As evidenced, the RuO〈sub〉2〈/sub〉(20)-AC composite has a promising salt adsorption capacity of 11.26 mg/g, which is 3.7-fold higher than that of pristine AC. Therefore, using the RuO〈sub〉2〈/sub〉(20)-AC composite as the cathode, an enhanced desalination performance can be achieved through a mixed capacitive-Faradaic process, resulting from two removal mechanisms of capacitive electrosorption and pseudocapacitive redox reactions. This work provides an efficient strategy to utilize RuO〈sub〉2〈/sub〉 on porous carbon-based substrates to improve CDI performance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 296〈/p〉 〈p〉Author(s): Zesheng Li, Ling Zhang, Xi Chen, Bolin Li, Hongqiang Wang, Qingyu Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Newly three-dimensional (3-D) graphene-like carbon nanosheet network is synthesized by a simple and efficient buried-protection KOH activation technology with a surfactant (Tween-20) as carbon source (molecular precursor). The as-synthesized material possesses favorable three-dimensional network structure and hierarchical porous structure (with a specific surface area of 2017.3 m〈sup〉2〈/sup〉 g〈sup〉−1〈/sup〉). As a promising supercapacitor electrode, a relatively high specific capacitance of 316.8 F g〈sup〉−1〈/sup〉 at a current density of 1 A g〈sup〉−1〈/sup〉 in 1 mol L〈sup〉−1〈/sup〉 KOH aqueous solution, along with good cycling stability (with a 92.5% retention rate after 2000 cycles) are demonstrated for the as-prepared electrode. The 3-D graphene-like carbon nanosheet network material exhibits ideal capacitive behavior indicating a promising electrode material for high-performance supercapacitors.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618324666-egi10K5SW95X08.jpg" width="465" alt="Image" title="Image"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 295〈/p〉 〈p〉Author(s): Haifeng Yu, Lei Xu, Haiyan Wang, Hao Jiang, Chunzhong Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Searching for high-performance electrode materials with rapid charge/discharge and high cycling stability is pivotal to broaden the applications of lithium-ion batteries (LIBs). Herein, we report a simple nanochannel-confined synthesis technology of ultrafine Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 (〈10 nm) nanoparticles encapsulated into carbon nanotubes (CNTs) hybrids for LIBs electrode materials. The three crystal forms of Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 can be respectively obtained simply by changing the temperature of thermal treatment. The ultrafine Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 nanoparticles dominated by the inner diameter of CNTs expose very high lithiation active sites. The fascinating nanostructure can also possess high structural stability with rapid electron transfer rate. Consequently, the orthorhombic Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉/CNTs hybrids show a maximum specific capacity of 207 mAh g〈sup〉−1〈/sup〉 at 0.1 A g〈sup〉−1〈/sup〉, which can be maintained 170 mAh g〈sup〉−1〈/sup〉 after 1000 cycles. More importantly, a specific capacity of 108 mAh g〈sup〉−1〈/sup〉 can still be achieved even at 10 A g〈sup〉−1〈/sup〉, much higher than CNTs surface loaded Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 nanoparticles hybrids. This work provides a channel-space confined synthesis insight for constructing novel electrode materials for high-rate and long-life LIBs.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618324897-fx1.jpg" width="275" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 295〈/p〉 〈p〉Author(s): Sandra Pluczyk, Heather Higginbotham, Przemyslaw Data, Youhei Takeda, Satoshi Minakata〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Exploration of optoelectronic properties of novel phosphorus-embedded π-conjugated compounds would provide us with fundamental information about the design of hitherto unknown electroactive organic materials. Herein, detailed photophysical and electrochemical profiles of a series of benzene-cored diketophosphanyl compounds were investigated with steady and time-resolved spectroscopic and spectroelectrochemical techniques. The comparative studies revealed the impact of phosphorus and nitrogen atoms on their triplet energies and on the behaviour of electrochemical processes to form radical species.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S001346861832396X-fx1.jpg" width="336" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Jacek Ryl, Lukasz Burczyk, Artur Zielinski, Mateusz Ficek, Artur Franczak, Robert Bogdanowicz, Kazimierz Darowicki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The electrochemical active surface area (EASA) of polycrystalline boron-doped diamond (BDD) electrodes is heterogeneous and can be affected by numerous factors. There is a strong need for proper consideration of BDD heterogeneity in order to improve this material's range of application in electrochemistry. Localized changes in surface termination due to the influence of oxidation agent result in increased surface resistance. The observed behavior of this characteristic feature varies among individual grains, depending on their crystallographic orientation. Still, there is not much information about this key factor in terms of its influence on the electrochemical response of BDD. In this study we compared two approaches towards BDD surface oxidation, namely: anodic polarization at potentiostatic and potentiodynamic conditions. The surface impedance measurements via Nanoscale Impedance Microscopy (NIM) allowed the confirmation of diversified propensity for the modification of surface termination in BDD. We showed that the NIM studies provide a deep understanding on the electrical characterization and variation of surface resistance in BDD electrodes. In order to evaluate the actual heterogeneity of electrochemical activity distribution, voltammetry, dynamic electrochemical impedance spectroscopy (DEIS) and scanning electrochemical microscopy (SECM) studies were performed. For each investigated electrode, departure from the Randles-Sevcik equation was observed, with its level depending on the surface heterogeneity and oxidation treatment, justifying the standardization of pre-treatment procedure and development of non-standard model for diffusion transport in proximity of BDD electrode.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618327488-egi10DT7MFLQCV.jpg" width="491" alt="Image 107" title="Image 107"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Xiaohe Ji, Cheng Yang, Wenjuan Fang, Hua Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Although graphene hydrogel (GH) as counter electrode (CE) has been reported to improve the efficiency of quantum dot sensitized solar cells (QDSCs), the lower current density than that of commonly used brass-based CE is still a limitation. In this work, the investigated CEs containing GH and Cu〈sub〉2〈/sub〉S have further improved current density with the resultant high efficiency via controlling the reduction level and property of GH. Results show that the composite CEs in which GH was fabricated via chemical reduction technique exhibit higher current density accompanied by higher voltage and fill factor, leading to the dramatically high efficiency. In comparison with that of hydrothermal reduction, the outperformance of chemically-reduced GH is attributed to the more reduction level, resulting in higher conductivity and better catalytic activity with synergistic effect of Cu〈sub〉2〈/sub〉S catalysts. The impressively high efficiency of 11.51% has been obtained for the model CdSeTe QDSC, respectively 23.9% and 7.2% higher than that of brass and thermally-reduced GH based CEs. The exciting results meet our expectations of further improving efficiency through higher current density. The as-prepared GH based composite CE has also been exploited to assemble fully flexible QDSC with high efficiency of 2.84%.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618320103-fx1.jpg" width="383" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Andrzej Bobrowski, Agnieszka Królicka, Julia Śliwa, Jerzy Zarębski〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An in-situ plated tellurium film electrode at the glassy carbon substrate (TeF-GCE) was applied for a sensitive catalytic voltammetric determination of molybdenum in the presence of 0.08 mM of mandelic acid (HA), 0.1 M of KClO〈sub〉3〈/sub〉, 0.01 M of HCl and 150 μg L〈sup〉−1〈/sup〉 of Te(IV). The performed cyclic and square-wave voltammetric measurements indicate that the investigated catalytic system at the TeF-GCE involves electrocatalysis of the second kind, in which a composite complex between the catalyst Mo(V)-A and ClO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 ions forms, and the subsequent irreversible electrochemical reaction yields the catalyst and electroinactive ClO〈sub〉2〈/sub〉〈sup〉−〈/sup〉 ions. The applied analytical procedure was based on 120 s of deposition of Te film at −0.6 V, followed by differential pulse polarization of the electrode from 0 V to −0.6 V. The sensitivity of the method was 4.02 μA/(μg L〈sup〉−1〈/sup〉) and the catalytic voltammetric response was proportional to the concentration of molybdenum within the range from 0.02 to 0.14 μg L〈sup〉−1〈/sup〉. The limit of detection was found to be 0.004 μg L〈sup〉−1〈/sup〉 of Mo(VI), which makes the catalytic voltammetric method suitable for the quantification of Mo ultratraces in surface waters.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Stefan Barwe, Corina Andronescu, Ruben Engels, Felipe Conzuelo, Sabine Seisel, Patrick Wilde, Yen-Ting Chen, Justus Masa, Wolfgang Schuhmann〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The development of bifunctional oxygen electrodes is a key factor for the envisaged application of rechargeable metal-air batteries. In this work, we present a simple procedure based on pyrolysis of polybenzoxazine/metal metalloid nanoparticles composites into efficient bifunctional oxygen reduction and oxygen evolution electrocatalysts. This procedure generates nitrogen-doped carbon with embedded metal metalloid nanoparticles exhibiting high activity towards both, oxygen reduction and oxygen evolution, in 0.1 M KOH with a roundtrip voltage of as low as 0.81 V. Koutecký-Levich analysis coupled with scanning electrochemical microscopy reveals that oxygen is preferentially reduced in a 4e〈sup〉−〈/sup〉 transfer pathway to hydroxide rather than to hydrogen peroxide. Furthermore, the polybenzoxazine derived carbon matrix allows for stable catalyst fixation on the electrode surface, resulting in unattenuated activity during continuous alternate polarisation between oxygen evolution at 10 mA cm〈sup〉−2〈/sup〉 and oxygen reduction at −1.0 mA cm〈sup〉−2〈/sup〉.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618327452-fx1.jpg" width="245" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Qilin Liu, Xiaoqin Li, Yu Wu, Miaoqing Qing, Guangqun Tan, Dan Xiao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Capacitive deionization (CDI) is a powerful brackish water desalination technology and one of the effective measures to solve the shortage of freshwater resources. With the hope to design a material with efficient desalination performance, we develop a simple, fast and green method to prepare porous carbon. The pine pollen disruption powder is used as the carbon precursor to prepare porous carbon by a simple high temperature calcination. We explore the effect of temperature on the morphology, pores and electrosorption performance, discovering the material calcined at 900 °C (PC-900) is the optimal one. PC-900 exhibits the electrosorption capacity of 7.25 mg g〈sup〉−1〈/sup〉 at a low initial concentration of NaCl (50.5 μS cm〈sup〉−1〈/sup〉) and 19.43 mg g〈sup〉−1〈/sup〉 at a high initial concentration of NaCl (500 μS cm〈sup〉−1〈/sup〉). Moreover, the synthesized material also shows improved exhibited salt removal rate, charge efficiency, reversibility and recycling stability. The excellent desalination performance is mainly attributed to the large specific surface area and suitable pore size. This result demonstrates that is porous carbon derived from pine pollen disruption powder is a promising CDI electrode material for brackish water desalination.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618327701-fx1.jpg" width="318" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Alexander Mozalev, Jaromir Hubalek〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Arrays of 0- and 1-dimensional noble-metal nanostructures aligned on solid substrates are in demand for nanocatalysis, bio- and optical sensing, or biomolecular analysis. Here we introduce a range of advances based on a systematic research towards the porous-anodic-alumina (PAA)-assisted on-substrate arrays of gold nanostructures, such as rods and spheres, spatially-separated and highly aligned on a metal or semiconductor supporting layer via a blend of the anodizing, re-anodizing, and post-anodizing treatments applied to a thin layer of Al superimposed on selected valve metals (W, Ti, Hf), metal bilayers (W/Ti), or binary metal alloy layers (W-Ti). The achievements are due to (1) the improved self-organization in the PAA thin films during the self-localizing high-current anodization of the upper Al layer at challenging potentials ranging 100–250 V and 20 to 5 V, and (2) the enhanced penetration of the alumina barrier layer by the undergrowing metal oxide due to the increasing polarization (re-anodizing). The protrusions of the undergrown metal oxide can be either selectively dissolved away providing perfect nanoholes in the alumina barrier layer or left as formed in the barrier layer and annealed in vacuum to increase their electron conductance and serve as the supports for subsequent metal electrodeposition. Additionally, the in-situ amplitude-modulated constant-current pulse deposition mode combined with the original surface-wiping technique to remove the overdeposited gold allow for smooth nucleation and uniform finishing of perfect arrays of on-substrate gold nanospheres and nanorods, having diameters from 10 to over 250 nm and length up to 2.5 μm.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618326768-egi107TL78Z2BR.jpg" width="448" alt="Image 107782" title="Image 107782"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Na Wu, Xue Zhang, Can Ma, Ya-Ru Shi, Jin-Ming Zhou, Zhe Wang, Hui Liu, Xian-Xiang Zeng, Yu Wei〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A simple strategy which combines the treatment of industrial wastewater with the preparation of electrode materials was proposed in this work. And the industrial wastewater is the only iron source for the material preparation. The preparation method in this work is facile, economical and environment-friendly which includes two simple steps of low-temperature aqueous solution and one-step calcination. Moreover two kinds of high performance Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 anode materials (α-/γ-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nano spheres, respectively) with isomerism can be obtained by simply adjusting calcination temperatures. Both of the α-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and γ-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanospheres show good lithium storing reversibility when used as anode materials in LIBs. Furthermore the as-prepared α-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nano-electrode with lower electrochemical impedance exhibit a far better electrochemical performance (about 74.1% capacity retention (calculated based on the lithiation) from the 1st to 5th cycle) than the γ-one (only 39.0% capacity retention from the 1st to 5th cycle). The results here provide economical yet environment-friendly strategies for developing advanced anode material demanding both high energy and long lifespan for full-cell lithium battery.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Mariangela Longhi, Serena Arnaboldi, Elena Husanu, Sara Grecchi, Ivo Franco Buzzi, Roberto Cirilli, Simona Rizzo, Cinzia Chiappe, Patrizia Romana Mussini, Lorenzo Guazzelli〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In spite of the increasing fundamental and practical interest of electrochemistry in ionic liquids (ILs), exploration of 〈em〉chiral〈/em〉 ionic liquids (CILs) in view of 〈em〉enantioselective〈/em〉 electrochemistry and electroanalysis is surprisingly overdue. In this study a family of chiral ionic liquids (CILs) based on natural chiral building blocks, of easy synthesis, is detailedly characterized in terms of thermal and electrochemical properties, achieving valuable information about structure−property relationships on account of the systematicity of available family terms. Moreover, they are submitted to a series of chiral electroanalysis tests. Cyclic voltammetry in bulk CILs or with CIL as additives in a bulk achiral ionic liquid IL, shows small but statistically significant potential differences for the enantiomers of two quite different chiral probes, an interesting result since enantiodiscrimination in terms of potential differences in chiral voltammetry (more desirable respect to current differences) has been only seldom obtained so far. The present first example of enantioselective voltammetry in CIL media 〈em〉with stereocenters as localized chirality sources〈/em〉 also offers an important and so far missing confirmation of the intrinsically superior level of the 〈em〉inherent chirality〈/em〉 strategy, recently resulting in larger potential differences with the same protocols implemented in "inherently chiral" ionic liquid media. Furthermore, an alternative transduction mode, based on electrochemical impedance spectroscopy EIS, is proposed to effectively highlight the enantiodiscrimination ability of CIL media in analytical experiments.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618327580-fx1.jpg" width="288" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Xiulan Qin, Ying Huang, Ke Wang, Tingting Xu, Yanli Wang, Panbo Liu, Yuan Kang, Yang Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Novel hierarchically porous titanium-metal organic frameworks/nitrogen-doped graphene (Ti-MOFs/NG) nanocomposite derived from titanium-metal organic frameworks (Ti-MOFs) and the nitrogen-doped graphene (NG) has been originally synthesized successfully. Notably, the Ti-MOFs/NG nanocomposite has been for the first time investigated in detail, as oxygen reduction reaction (ORR) catalyst of cathodic materials for fuel cells. The results show that the Ti-MOFs/NG nanocomposite possesses excellent ORR performances, whether in alkaline or acidic medium, due to existences of the Ti〈sub〉3〈/sub〉N〈sub〉2-x〈/sub〉, C〈sub〉2〈/sub〉O〈sub〉7〈/sub〉Ti〈sub〉2.3〈/sub〉, H〈sub〉2〈/sub〉Ti〈sub〉5〈/sub〉O〈sub〉11〈/sub〉, Ti and TiO active ORR segments. Specifically, the onset potential (E〈sub〉0〈/sub〉) and the Tafel slope value of the Ti-MOFs/NG nanocomposite are 1.14 V and 17.84 mV dec〈sup〉−1〈/sup〉 in 0.1 M HClO〈sub〉4〈/sub〉, respectively. Similarly, high ORR efficiency of the Ti-MOFs/NG nanocomposite also exhibit in alkaline medium. The relative current density can still keep 99.88% of the original value after 10800 s measurements in 0.1 M KOH. Additionally, small electrochemical impedance and excellent tolerance toward fuel molecules have been exhibited in both electrolytes. These ORR properties are superior to those of most of previously reported materials derived from other MOFs, in both alkaline and acidic media. Thus, the Ti-MOFs/NG nanocomposite is as a novel promising candidate for ORR catalyst to solve the main problems of sluggish reaction kinetics of the ORR, high cost of precious metal catalysts and low durability of the traditional catalysts, applied to fuel cells, metal-air batteries and further to water splitting in energy conversion and storage devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Bei Qian, Marios Michailidis, Matt Bilton, Theo Hobson, Zhaoliang Zheng, Dmitry Shchukin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nanocontainers with controlled release properties have been used in self-healing coatings for many years. However, the spontaneous leakage of the small molecular weight inhibitors from the nanocontainers promoted the development of nanovalves or gatekeepers to control inhibitor release. Herein, we demonstrate a facile method to encapsulate corrosion inhibitor in mesoporous silica nanoparticles (MSNs) with the help of tannic acid complexes, which endow the inhibitor loaded MSNs with pH-controlled release function. Commercial water-borne alkyd coating impregnated with 2 wt% of benzotriazole-loaded nanocontainers presented significant self-healing effect after 20 days of immersion in 0.1 M NaCl solution from both released benzotriazole and tannic acid as confirmed by electrochemical impedance spectroscopy and microscopy. The impedance modulus of coating with nanocontainers increased from 4.7 × 10〈sup〉4〈/sup〉 Ω cm〈sup〉2〈/sup〉 to 1.8 × 10〈sup〉5〈/sup〉 Ω cm〈sup〉2〈/sup〉 after 15 days of immersion.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Li Shao, Ling Zhou, Lishan Yang, Chuankun Jia, Chunhui Wang, Shuai Hu, Xifeng Zeng, Chunming Yang, Chenghuan Huang, Youyuan Zhou, Xiaoming Xi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Surface structural engineering has been widely applied to improve the electrochemical performances of LiCoO〈sub〉2〈/sub〉 cathodes, especially for applications at high operation voltages (〉4.4 V vs. Li) and elevated working temperature (≥50 °C). In this report, Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 layer with an average thickness of 8 nm was firstly obtained on the LiCoO〈sub〉2〈/sub〉 surface, and then was transformed into LiAlO〈sub〉2〈/sub〉/LiCo〈sub〉1-x〈/sub〉Al〈sub〉x〈/sub〉O〈sub〉2〈/sub〉 double-layers by a facile heating treatment. This novel double-layers structure was clearly presented by high resolution transmission electron microscopy (HRTEM) and depth profile of X-ray photoelectron spectroscopy (XPS). Due to the chemical/electrochemical stability of the LiAlO〈sub〉2〈/sub〉 layer and high Li〈sup〉+〈/sup〉 conductivity of the LiCo〈sub〉1-x〈/sub〉Al〈sub〉x〈/sub〉O〈sub〉2〈/sub〉 layer, this cathode with hierarchical structure achieved higher capacity and better cycling stability than the Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 coated LiCoO〈sub〉2〈/sub〉 cathode at both 25 and 55 °C. In addition, this LiAlO〈sub〉2〈/sub〉/LiCo〈sub〉1-x〈/sub〉Al〈sub〉x〈/sub〉O〈sub〉2〈/sub〉/LiCoO〈sub〉2〈/sub〉 cathode maintained the capacity of 178.1 mA h g〈sup〉−1〈/sup〉 (73% capacity retention) after 500 cycles (3.0–4.5 V, 1C), which is very promising to be used in severe operation conditions such as high temperature and voltage.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Huimin Wang, Denis Y.W. Yu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Despite advances in traditional lithium-ion batteries in the past decades, its high cost has always been a bottleneck for large-scale applications. In this work, we demonstrate it is possible to replace expensive cathodes such as LiCoO〈sub〉2〈/sub〉 with inexpensive stainless steel to store energy via a stripping/deposition mechanism: during charging, the stainless-steel cathode removes charges by releasing metal ions into the electrolyte, and during discharge, the metal ions re-deposit on the electrode reversibly. An anion exchange membrane allows passage of anions to balance the charge and prevents cross-over of cations. We show here a battery with a stainless-steel cathode and a lithium metal anode with a high discharge voltage of 2.5 V and good reversibility. We also study the mechanism at the stainless-steel electrode, as well as the kinetics of the battery system. Our work can potentially reduce the cost of energy storage by turning common construction materials into cathode materials. In addition, a metal cathode undergoing stripping/deposition gives a theoretical energy density comparable to lithium-sulfur batteries and provides a new exciting direction for future energy storage development.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Akanksha Joshi, Shubra Lalwani, Gurmeet Singh, Raj Kishore Sharma〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present study elaborates facile approach to generate active sites in cashew nut shaped silica (SiO〈sub〉2〈/sub〉). These active sites are attributed to the high concentration of oxygen vacancies and bimodal mesoporosity in silica owing to etching and calcination treatment. In the etched calcined silica (ECS), mesopores act as buffered spaces, whereas, OVs provide high carrier/donor density (3 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mo〉×〈/mo〉〈msup〉〈mrow〉〈mn〉10〈/mn〉〈/mrow〉〈mrow〉〈mn〉24〈/mn〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉cm〈sup〉−3〈/sup〉). High density of carriers/donor reduces the distance between active sites (2.5 nm) further enhancing the rate of electron transfer. Consequent to the unique combination of OVs and bimodal mesoporosity, ECS exhibits high electrochemically accessible surface area (3170 m〈sup〉2〈/sup〉 g〈sup〉−1〈/sup〉) and excellent charge storage in ECS||ECS cell (∼337 F g〈sup〉−1〈/sup〉 at 1 A g〈sup〉−1〈/sup〉). In addition, the symmetric cell (ECS||ECS) delivers maximum energy density of 46.86 Wh Kg〈sup〉−1〈/sup〉 at power density of 537.59 W kg〈sup〉−1〈/sup〉 with respectable capacitance retention (111% after 10,000 cycles). Remarkably, the solid state flexible device unveiled energy density of 2.16 Wh Kg〈sup〉−1〈/sup〉 at 166.05 W kg〈sup〉−1〈/sup〉 even under the bent state retaining 165% of its capacitance up till 3000 cycles. This work essentially highlights the synergism between mesoporosity and oxygen vacancies on the charge storage characteristics of silica.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Synergistic contribution of bimodal mesopores and oxygen vacancies in silica for excellent supercapacitive performance.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618327312-fx1.jpg" width="250" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Antonio Doménech-Carbó, María Teresa Doménech-Carbó, Amparo Castelló-Palacios, Vicent Guerola-Blay, Eva Pérez-Marín〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The voltammetry of immobilized particles (VIMP) methodology was applied to discriminate the oil painting production of a series of seven painters/workshops that worked in Valencia (Spain) between ca. 1530 and ca. 1650. When submicrosamples used for cross-section FESEM/EDX analysis were attached to graphite electrodes in contact with aqueous acetate buffer, well-defined responses were obtained. The reductive processes of lead pigments (lead white and lead-tin yellow) overlapped those associated to the lead soaps and other species resulting from the pigment-oil binder interaction in the sample. Such responses, which are theoretically modeled, were sensitive to changes in paint type and dose and thus provided a painter/workshop-characteristic voltammetric response defining a usable electrochemical fingerprint for authorship assessments.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618326963-fx1.jpg" width="157" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Aria Kahyarian, Srdjan Nesic〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the context of H〈sub〉2〈/sub〉S corrosion of mild steel, the direct electrochemical reduction of H〈sub〉2〈/sub〉S is currently believed to be the main contribution of this species to cathodic currents. That is perhaps due to the distinct behavior of the cathodic polarization curves observed in the presence of H〈sub〉2〈/sub〉S, as compared to those obtained in strong acids solutions or in the presence of other weak acids such as carboxylic acids and carbonic acid. In the presence of aqueous H〈sub〉2〈/sub〉S, the cathodic polarization curves show a “double wave” shape, that is widely considered to be the result of the direct reduction of H〈sub〉2〈/sub〉S. In the present study, the mechanism of H〈sub〉2〈/sub〉S corrosion of mild steel is theoretically investigated with the focus on the buffering ability of H〈sub〉2〈/sub〉S. It is shown that all characteristic behaviors of cathodic currents that were previously associated with the direct reduction of H〈sub〉2〈/sub〉S, including the “double wave”, can be fully explained in terms of the H〈sub〉2〈/sub〉S dissociation reaction and its buffering effect. In order to further evaluate this mechanistic argument, a comprehensive mathematical model for the H〈sub〉2〈/sub〉S system was developed and the calculated cathodic polarization curves were compared with the existing experimental data in the open literature. The results showed that the model, built with H〈sup〉+〈/sup〉 reduction as the sole cathodic reaction, is able to reasonably capture all characteristic behavior of cathodic currents, further supporting this mechanistic argument.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Yaohui Liang, Nan Li, Fengyan Li, Zhiwei Xu, Yanli Hu, Miaolei Jing, Kunyue Teng, Xuemei Yan, Jie Shi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Further modification of carbon and transition metal composites has become a hot spot in the preparation of anode materials for lithium ion battery, including various morphologies, nitrogen doping and porous introduction. However, the synergistic effect of specific surface area and nitrogen doping content of composite materials on the electrochemical performance as anode materials for lithium ion batteries has not been revealed. In this paper, the carbon nanofibers loaded with titanium dioxide are fabricated via electrospinning method followed by calcination process with simple addition admixture of diisopropyl azodiformate in precursor solution. The pores are introduced into the composite with controllable nitrogen doping and surface area simultaneously. The specific capacity of titanium dioxide @carbon nanofibers has been increased from 192.2 mAh g〈sup〉−1〈/sup〉 to 336 mAh g〈sup〉−1〈/sup〉 due to the increased nitrogen content of the composite from 7.18% to 10.21%, and elevated specific surface area from 67.23 to 111.15 m〈sup〉2〈/sup〉 g〈sup〉−1〈/sup〉, which can endow the composite superior conductivity and more active sites. The capacity contribution of the total specific capacity has decreased from 60.8% to 44.7% compared with original sample, proving that increasing diffusion controlled Faradaic Li-ion insertion origins from nitrogen doping.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618327105-fx1.jpg" width="456" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Yuebin Yang, Hui Xu, Shanxing Wang, Yuanfu Deng, Xianying Qin, Xusong Qin, Guohua Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Li-ion batteries have held a dominant position in the energy storage area for decades. However, due to the limitation of its chemistry, the energy density of Li-ion batteries is limited to ∼300 W h kg〈sup〉−1〈/sup〉. In recent years, more attention has been paid to the Li-S batteries that are environmentally friendly, cost-effective and high energy density (theoretical value of cathode: ∼2600 W h kg〈sup〉−1〈/sup〉). In this study, carbonized polydopamine (C-PDA)-coated hollow carbon nanofibers (CNFs) with TiO〈sub〉2〈/sub〉 nanoparticles interspersed in the void space between the CNF skeleton and carbon coating layer were subtly designed. The C-PDA/TiO〈sub〉2〈/sub〉/CNF composite (CTC) was integrated with the commercial separator as a polysulfide filter to achieve high-performance Li-S batteries. It is reveals that the CTC coating layer could effectively filter and reactivate the dissolved polysulfides to achieve a stabilized sulfur-based cathode. The Li-S battery assembled by this integrated separator and the regular cathode (sulfur/Ketjen black) with 72.7 wt% of sulfur achieved a high specific capacity and low decay rate (632.5 mAh g〈sup〉−1〈/sup〉 at the first cycle and 0.06% per cycle) at 2.0C for 500 cycles. These good results indicate that the C-PDA/TiO〈sub〉2〈/sub〉/CNF-modified separator could be a promising separator candidate for high performance Li-S batteries.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Lewis C. Yule, Cameron L. Bentley, Geoff West, Barbara A. Shollock, Patrick R. Unwin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The development of tools that can probe corrosion related phenomena at the (sub)microscale is recognized to be increasingly important in order to understand the surface structural factors (grain orientation, inclusions 〈em〉etc.〈/em〉) that control the (electro)chemical stability (corrosion susceptibility, pitting, passivity 〈em〉etc.〈/em〉) of metal surfaces. Herein we consider the application of scanning electrochemical cell microscopy (SECCM), a relatively new member of the electrochemical droplet cell (EDC) family, for corrosion research and demonstrate the power of this technique for resolving structure and activity at the (sub)microscale. Hundreds of spatially-resolved (2 μm droplet size) potentiodynamic polarization experiments have been carried out on the several hours timescale and correlated to complementary structural information from electron backscatter diffraction (EBSD) and energy dispersive x-ray spectroscopy (EDS) in order to determine the effect of grain orientation and inclusions on electrochemical processes at low carbon steel in neutral solution (10 mM KNO〈sub〉3〈/sub〉). Through this approach, it has been shown unequivocally that for the low index planes, anodic currents in the passive region (an indicator of corrosion susceptibility) are greatest on (101) planes compared to (100) and (111) planes. Furthermore, individual sub-micron MnS inclusions have been probed and shown to undergo active dissolution followed by rapid repassivation. This study demonstrates the high versatility of SECCM and the considerable potential of this technique for addressing structure-activity problems in corrosion and electromaterials science.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 296〈/p〉 〈p〉Author(s): Vera Smulders, Nina Simic, Adriano S.O. Gomes, Bastian Mei, Guido Mul〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In electrochemical production of sodium chlorate from brine solutions, an intriguing function of sodium (di)chromate is to inhibit cathodic reduction of oxychlorides, while maintaining effective reduction of water to form hydrogen. Using an electrochemical Quartz Crystal Microbalance (eQCM) and a Rotating Ring Disk Electrode (RRDE; Au disk, Pt ring), we analyzed the deposition of reduced Cr-species formed from reduction of Cr〈sup〉VI〈/sup〉O〈sub〉4〈/sub〉〈sup〉2−〈/sup〉 on Au electrodes. Generally, the current induced by reduction of Cr〈sup〉VI〈/sup〉O〈sub〉4〈/sub〉〈sup〉2−〈/sup〉 is significantly larger than the accumulated amount of weight deposited on the Au electrode. Deconvolution of the reductive peak reveals two processes that can be differentiated by varying rotation speed. We therefore propose soluble Cr〈sup〉V〈/sup〉O〈sub〉4〈/sub〉〈sup〉3−〈/sup〉 is formed by reduction of Cr〈sup〉VI〈/sup〉O〈sub〉4〈/sub〉〈sup〉2−〈/sup〉, followed by consecutive reduction of Cr〈sup〉V〈/sup〉O〈sub〉4〈/sub〉〈sup〉3−〈/sup〉 to primarily soluble Cr〈sup〉III〈/sup〉(OH)〈sub〉4〈/sub〉〈sup〉-〈/sup〉. Simultaneously, reduction of Cr〈sup〉V〈/sup〉O〈sub〉4〈/sub〉〈sup〉3−〈/sup〉 also leads to the formation of a monolayer of Cr〈sup〉III〈/sup〉(hydr)oxide. This monolayer significantly inhibits the further reduction of Cr〈sup〉VI〈/sup〉O〈sub〉4〈/sub〉〈sup〉2−〈/sup〉, but allows the film to reach a maximum thickness of approximately 1.85 nm by reduction of surface adsorbed Cr〈sup〉V〈/sup〉O〈sub〉4〈/sub〉〈sup〉3−〈/sup〉 and/or de-hydroxylation of Cr〈sup〉III〈/sup〉(OH)〈sub〉4〈/sub〉〈sup〉-〈/sup〉. The observation that limitation of film growth is due to film-induced inhibition of reduction of Cr〈sup〉VI〈/sup〉O〈sub〉4〈/sub〉〈sup〉2−〈/sup〉, and significant solubility of Cr〈sup〉III〈/sup〉(OH)〈sub〉3〈/sub〉 in the form of Cr〈sup〉III〈/sup〉(OH)〈sub〉4〈/sub〉〈sup〉-〈/sup〉, will aid in the search of a non-toxic chrome-free alternative for inhibition of cathodic reduction of oxychlorides and selective hydrogen evolution in the chlorate process.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Redox chemistry leading to deposition of Cr〈sup〉III〈/sup〉O〈sub〉x〈/sub〉 from Na〈sub〉2〈/sub〉Cr〈sub〉2〈/sub〉O〈sub〉7〈/sub〉 on a Au electrode.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618325295-fx1.jpg" width="268" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): I. Novak Jovanović, D. Jadreško, A. Miličević, M. Hranjec, N. Perin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The electrochemical behaviour of potential antitumor benzimidazole derivatives (benzo[〈em〉b〈/em〉]thieno[2,3-〈em〉b〈/em〉]pyrido[1,2-〈em〉a〈/em〉]benzimidazoles and benzimidazo[1,2-〈em〉a〈/em〉]quinolines) bearing one or two piperazine substituents was studied at a glassy carbon electrode (GCE) using cyclic and square-wave voltammetry in a wide range of pH values and potential scan rates. The electrochemical oxidation of the studied benzimidazoles proceeded 〈em〉via〈/em〉 one or two electrode reactions assigned to the oxidation of one or two piperazine substituents, respectively. The oxidation of piperazine ring involved the transfer of two electrons and one proton in a pH-dependent, kinetically controlled electrode reaction, followed by a homogenous chemical reaction (EC mechanism). Both the reactants and the products of EC reactions were strongly adsorbed on the GCE surface. The electrochemical reduction occurred in one quasireversible, pH-dependent step, followed by a chemical transformation of the electrochemically formed product. The proposed reduction mechanism was related to the cyano moiety. The assignment of electroactive sites in molecules of interest was confirmed by theoretically calculated, using the PM6 method, differences of Net atomic charges between the cation (or anion) and neutral molecule.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): T.W. Cain, C.F. Glover, J.R. Scully〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The corrosion behavior of solid solution Mg-xSn (x = 1, 5, 10 wt%) alloys is explored as a function of Sn content in chloride-containing conditions. A suite of 〈em〉in situ〈/em〉 electrochemical techniques and an 〈em〉in situ〈/em〉 scanning vibrating electrode technique (SVET) is utilized to assess free corrosion rates and the extent of cathodic activation. The latest advances in improving the corrosion resistance of Mg alloys have demonstrated that micro-alloying with As or Ge can greatly lower corrosion rates compared to pure Mg and retard cathodic activation to a substantial degree. To broaden the options for suitable non-toxic alloying elements beyond Ge, the current article demonstrates a decreasing corrosion rate by 77%, 85% and 95% for Sn additions of 1%, 5% and 10% (wt%) respectively, when compared to HP Mg freely corroding in 0.6 M aqueous NaCl. A corrosion film formed on Mg-10Sn which displays superior barrier properties. Polarization resistance (R〈sub〉p〈/sub〉) values consistently one order of magnitude greater than that obtained on HP Mg, and the other Mg-Sn alloys, over a 24 h immersion period is demonstrated. Furthermore, the extent of cathodic activation for Mg-10Sn is shown to be reduced by 94% relative to HP Mg. The work presented herein provides advancements in the understanding of corrosion resistant Mg alloys and is pertinent to the potential use of Mg-Sn alloys in transport applications, battery electrode materials and as a candidate sacrificial anode for the cathodic protection of Mg alloy AZ31B-H24. Prospects for protection are discussed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Ting-Feng Yi, Jie Mei, Ying Xie, Shaohua Luo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Spherical flowerlike NiOand NiO@CeO〈sub〉2〈/sub〉(2.5, 5.0 and 7.5 wt%) composites are successfully prepared by a simple hydrothermal method. NiOmaterials show spherical flower morphology with a radius of 4–5 μm, and the CeO〈sub〉2〈/sub〉nano-particles deposit on the surface of NiOpetals (nanosheets), and then form porous NiO@CeO〈sub〉2〈/sub〉flower-like microspheres. NiOpetals are covered with electrochemical active CeO〈sub〉2〈/sub〉nanoparticles, leading to an advantageous synergistic storage effect due to the charge redistribution in the NiO|CeO〈sub〉2〈/sub〉interface, which can decrease the polarization and accelerate the ion diffusion. NiO@CeO〈sub〉2〈/sub〉(5.0 wt%) electrode shows an excellent specific capacitance of 960.4 F g〈sup〉−1〈/sup〉at 20 A g〈sup〉−1〈/sup〉and keeps about 95.84% capacitance retention after 10000 cycles. Whereas the NiO, NiO@CeO〈sub〉2〈/sub〉(2.5 wt%) and NiO@CeO〈sub〉2〈/sub〉(7.5 wt%) electrodes have capacitances of 543.6, 1428 and 1143.6 F g〈sup〉−1〈/sup〉corresponding to capacitance retentions of 74.39%, 62.55% and 58.41% after 10000 cycles, respectively. The first-principles calculation exhibits that a strong chemical bond between O and Ce(Ni) can be formed at the interface, and such a chemical bonding between the two components is very helpful for the stabilization of the composite during repeated cycles, responsible for the good cycling performance of the materials. Therefore, the super capacitance and excellent cycling stability of NiO@CeO〈sub〉2〈/sub〉(5.0 wt%) electrode at high current density can be ascribed to the unique composition design and architectures.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S001346861832735X-fx1.jpg" width="392" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Jin-xing Kang, Ya-li Feng, Hao-ran Li, Zhu-wei Du, Xiang-yi Deng, Hong-jun Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The reductive dissolution of pyrolusite in simulated 〈em〉Acidithiobacillus ferrooxidans〈/em〉 bio-leaching medium was investigated. This study was performed in three stages. First, the advantageous electrochemical test conditions, parallel to the optimal bio-leaching conditions and adopting the Mn reduction rate, were determined by imitated electrolysis. The facilitation of 〈em〉A. ferrooxidans〈/em〉 on MnO〈sub〉2〈/sub〉 reduction is sensitive to pH and Fe(III) concentration. Second, electrochemical tests revealed that the reductive dissolution of manganese dioxide incorporated two single electron and proton steps-the first exchange of MnO〈sub〉2〈/sub〉 to MnO·OH, and then conversion to Mn(OH)〈sub〉2〈/sub〉 for diffusion. The results of transient and steady electrochemical measurements indicated that the first electron-transfer significantly affects the rate controlling step of Mn-leaching in control(9K) medium, while using 〈em〉A. ferrooxidans〈/em〉 and Fe(III) in the solution tends to enable the leaching rate to be controlled by the latter electron transfer step. Third, the analysis of semiconductor and carrier properties of passive films of pyrolusite formed in the different solutions, illustrated that the reductive dissolution of manganese dioxide tends to depend on the movement of the holes. The first electron preferentially reacts with the shallow energy level of the O-vacancy to form MnO〈sub〉2〈/sub〉〈sup〉·-〈/sup〉, which then absorbs H〈sup〉+〈/sup〉 to become MnO·OH. The second electron participates in the transformation of MnO·OH to (MnOH)(OH) and then to Mn(OH)〈sub〉2〈/sub〉. 〈em〉A. ferrooxidans〈/em〉 increases the carrier densities of the passivating film accelerating electron and proton transfer and Fe(III) primarily influences the shallow donor density of oxygen during the first electron-exchange. Additionally, the synergistic effect of 〈em〉A. ferrooxidans〈/em〉 and Fe(III) on manganese dioxide ore reductive leaching is confirmed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Nilanjan Chakrabarty, Amit K. Chakraborty〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Controlling the electrochemical performance of electrodes for application in supercapacitor has received large research interest in the recent years. Here we report the facile synthesis of a Ni(OH)〈sub〉2〈/sub〉 and carbon nanotubes based nanohybrid electrode and control its electrochemical performance for application in supercapacitor by La doping. A systematic investigation of the influence of a number of electrochemical parameters of measurement on the electrode properties is also presented. Structural and morphological analyses show formation of hexagonal nanoparticles (∼35 nm) well attached on the walls of carbon nanotubes (CNT) while elemental analysis confirms the success of La doping. The nanohybrid sample doped with 1 mol% La (with respect to Ni) appears to be the best performing electrode exhibiting specific capacitance of 2731 F/g at 1 A/g, energy density of 25 Wh/kg at power density of ∼1 kW/kg and capacity retention of 84% even after 5000 cycles which are higher than previously reported values for Ni(OH)〈sub〉2〈/sub〉 based electrodes and also the first of its kind in which β-Ni(OH)〈sub〉2〈/sub〉 has been combined with CNT and doped with La. Increase in the specific surface area as well as electrical conductivity of Ni(OH)〈sub〉2〈/sub〉 by incorporation of CNT and La dopants are the main reasons for the improved performance of the 1 mol% La doped composite whereas formation of insulating La(OH)〈sub〉3〈/sub〉 is responsible for the inferior performance of electrodes containing more than 1 mol% La. The charge storage mechanism has been found to be governed by both capacitive and diffusion processes at high scan rates but dominated by only diffusion process at low scan rates.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Kyeongmin Oh, Milad Moazzam, Geonhui Gwak, Hyunchul Ju〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Water crossover through the membrane of a vanadium redox flow battery system is not desirable because it floods one half-cell, diluting the vanadium solution on one side and consequently increasing the concentration of vanadium in the other half-cell. To analyze the effect of water crossover and the resultant electrolyte imbalance issue in the vanadium redox flow battery, herein we newly develop a water transport model and incorporate it into our previously developed 3D vanadium redox flow battery model. The model rigorously accounts for water production/consumption by the redox reaction of VO〈sup〉2+〈/sup〉/VO〈sub〉2〈/sub〉 and side reactions as well as various mechanisms of water crossover through the membrane arising from diffusion, electro-osmotic drag (EOD), and vanadium crossover. The numerical model is successfully validated against in situ data collected during experiments in which the electrolyte volumes and cell voltages are measured during charge–discharge cycles carried out under various current densities. The detailed simulation results clearly elucidate water crossover behaviors at different stages of charging and discharging, and further reveal the individual contributions of water crossover mechanisms to the overall electrolyte imbalance between the negative and positive sides of the VRFB system.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Jui-Hong Weng, Chih-Yu Lai, Lin-Chi Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper studies the electrochemical measurements of ferricyanide redox reaction with two symmetric Au microelectrodes in microfluidics under one-way and shuttle flow conditions. An equal-molar Fe(CN)〈sub〉6〈/sub〉〈sup〉3−〈/sup〉/Fe(CN)〈sub〉6〈/sub〉〈sup〉4−〈/sup〉 mixture was assayed with micro-fabricated Au electrodes placed inside a PDMS microfluidic channel by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) under a static or flow condition, respectively. It was found that the alignment and dimensions of microelectrodes played a crucial role in determining the electrochemical characteristics. Moreover, the redox characteristics were observed to be “tuneable” through microfluidic operations. Under the one-way flow mode, the CV response underwent a flow polarization effect that enhanced the downstream electrode reaction. Also, CV pattern transition from a typical wave shape to a sigmoidal curve was observed while increasing the flow rate for a microfluidic channel with a height ≤100 μm. In addition, steady-state CA responses instead of Cottrell-type currents were obtained owing to the convection-assisted mass transfer of ferricyanide. Under the shuttle flow mode, a liquid periodic motion effect was imposed on the CV measurement that resulted in oscillatory signals. By contrast, peak currents were produced in pairs periodically in the shuttle-mode CA, which were well-suited for redox quantitation and assessing the micro-mixing effect. Finally, both flow modes were proven effective to improve the detection sensitivity of microfluidic amperometry.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Two-electrode cyclic voltammetry and amperometry on a chip tuned with one-way and shuttle microfluidics.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618326112-fx1.jpg" width="347" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 296〈/p〉 〈p〉Author(s): Tankiso Lawrence Ngake, Johannes Hermanus Potgieter, Jeanet Conradie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The synthesis, identification and electrochemical properties are reported here, for a series of five novel and seven known amino substituted β-amino α,β-unsaturated ketones (bidentate N,O-ligands) of the type CH〈sub〉3〈/sub〉COCHC(NHR)CH〈sub〉3〈/sub〉, where R = H, Ph, CH〈sub〉2〈/sub〉Ph, CH(CH〈sub〉3〈/sub〉)〈sub〉2〈/sub〉, 〈em〉p〈/em〉-CF〈sub〉3〈/sub〉-Ph or 〈em〉p〈/em〉-〈sup〉〈em〉t〈/em〉〈/sup〉Bu-Ph (〈strong〉Series 1〈/strong〉), as well as type PhCOCHC(NHR)CH〈sub〉3〈/sub〉, where R = H, Ph, 〈em〉p〈/em〉-NO〈sub〉2〈/sub〉-Ph, 3,5-di-Cl-Ph, 2-CF〈sub〉3〈/sub〉-4-Cl-Ph, and also PhCOCHC(NHPh)CF〈sub〉3〈/sub〉 (〈strong〉Series 2〈/strong〉). The cyclic voltammograms measured in CH〈sub〉3〈/sub〉CN, generally exhibit both a chemically and electrochemically irreversible reduction peak between −1.2 V and −3.1 V 〈em〉vs〈/em〉 FcH/FcH〈sup〉+〈/sup〉, producing an unstable radical anion, for most of these 1,3-amino ketones. Only ligands PhCOCHC(NHPh)CH〈sub〉3〈/sub〉, PhCOCHC(NHPh)CF〈sub〉3〈/sub〉 and PhCOCHC(NH(〈em〉p〈/em〉-NO〈sub〉2〈/sub〉-Ph))CH〈sub〉3〈/sub〉, showed reversible electrochemical behaviour, at higher scan rates. Density functional theory (DFT) calculations proved the unpaired spin density in the radical anion to be distributed over the 〈em〉pseudo〈/em〉-aromatic O〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉N backbone of the 1,3-amino ketones, extending further over the phenyl rings of the phenyl-containing ligands. Various DFT calculated energies, such as the energy of the lowest unoccupied molecular orbital (the orbital into which the electron is added upon reduction), as well as the DFT calculated gas phase adiabatic electron affinities, relate linearly to the experimentally measured reduction potential. These obtained linear relationships confirmed that good communication via conjugation exists, between the R substituent on the amino group and the rest of the 1,3-amino ketone.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉The electrochemically irreversible reduction potential of a series of twelve amino-substituted β-amino α,β-unsaturated ketones, relates linearly to various computational chemistry calculated energies, thereby describing the electron withdrawing ability of each of the twelve amino substituents.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618326276-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Libing Yao, Meng Nie, Chongyang Zhu, Ran Cai, Weiwei Xia, Litao Sun, Feng Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Developing an electrode material with improved ionic transport dynamics in a battery has been the focus of research. Here, we report a facile one-step hydrothermal synthesis method to prepare anode material of ultra-small SnS nanocrystals (NCs) anchored on N-doped graphene nanosheets (SnS/N-G), which is expected to significantly the dynamics of lithium transport, enabling an exceptional capacity of 1120.3 mAh g〈sup〉−1〈/sup〉 at 0.1 A g〈sup〉−1〈/sup〉 after 130 cycles and superior rate capabilities of 446.3 and 340.7 mAh g〈sup〉−1〈/sup〉 at 2 and 3 A g〈sup〉−1〈/sup〉, respectively. Furthermore, the lithiation/delithiation behaviors of SnS/N-G anode were observed in real time using 〈em〉in situ〈/em〉 transmission electron microscopy to reveal the corresponding kinetics. By tracking the full lithiation procedure, 〈em〉in situ〈/em〉 electron diffraction and high-resolution TEM imaging found that the original SnS phase was firstly transformed to Sn phase by conversion reaction and then to Li〈sub〉22〈/sub〉Sn〈sub〉5〈/sub〉 phase by alloying reaction. Notably, a stable and reversible phase transformation was established between Li〈sub〉22〈/sub〉Sn〈sub〉5〈/sub〉 and Sn phases during subsequent charge-discharge cycles. In the meantime, the volume expansion-induced pulverization of SnS NCs was evidently alleviated by graphene matrix that not only provided a two-dimensional support to buffer the volume change, but also improved the ion migration kinetics, as corroborated by superior rate capability.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 296〈/p〉 〈p〉Author(s): Y.F. Liang, Y. Xia, S.Z. Zhang, X.L. Wang, X.H. Xia, C.D. Gu, J.B. Wu, J.P. Tu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A compositive synthesis of gel polymer electrolytes by blending poly(propylene carbonate) (PPC) into poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) as a polymer host is proposed. The blending polymer is produced by a facile solution casting method and ester groups of PPC are successful introduced into PVDF-HFP. The gel polymer electrolyte displays an excellent ion conductivity of 1.18 × 10〈sup〉−3〈/sup〉 S cm〈sup〉−1〈/sup〉, broad electrochemical window up to 4.8 V (vs. Li/Li〈sup〉+〈/sup〉) and outstanding electrochemical stability within rechargeable lithium batteries at room temperature. The improvement of ion conductivity is attributed to the decrease of polymer crystallizability and the increase of micro pores. The strategy of blending is promising for the modification of PVDF-HFP electrolyte and foreground application in next-generation solid energy conversion devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Mariana Spodaryk, Kun Zhao, Jie Zhang, Emad Oveisi, Andreas Züttel〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The electrochemical reduction of CO〈sub〉2〈/sub〉 to higher hydrocarbons is a very challenging process that has high potential for the storage of large amounts of renewable energy with a high gravimetric and volumetric energy density. The distribution of hydrocarbons from the electrocatalytic reduction of CO〈sub〉2〈/sub〉 is primarily determined by the interaction of the cathode material with the CO〈sub〉2〈/sub〉 in the electrolyte. While the research on the electrochemical CO〈sub〉2〈/sub〉 reduction focuses on the cathode metal and surface structure of the metals, recently evidence was found that the metal itself may not be the active species but rather the product formed from the metal and CO〈sub〉2〈/sub〉. In this paper, we report about the synthesis, catalytic activity and selectivity of nanostructured metal carbonate, i.e. malachite, as a highly active catalyst for the electrochemical synthesis of C2 hydrocarbons. These first results obtained on Cu〈sub〉2〈/sub〉(OH)〈sub〉2〈/sub〉CO〈sub〉3〈/sub〉 nanorod-structured “trees” show that carbonate, not the pure metal, is the active catalytic species. This new catalyst favors the production of ethylene (C〈sub〉2〈/sub〉H〈sub〉4〈/sub〉) and ethane (C〈sub〉2〈/sub〉H〈sub〉6〈/sub〉) with significantly higher Faradaic efficiency than that of the pure Cu surface.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Yejun Li, Chengan Liao, Kewei Tang, Ning Zhang, Weihong Qi, Haipeng Xie, Jun He, Kai Yin, Yongli Gao, Chundong Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Black phosphorus (BP), a new rediscovered 2-dimensional material, has gained enormous attention in the field of electrocatalysis, particularly for oxygen evolution reactions. However, its easily being oxidized nature and the bulk crystal structure restricts sufficient active sites, which severely hinders its potential applications in catalysis. Herein, BP nanosheets are prepared and deposited with Co(OH)〈sub〉2〈/sub〉 nanosheets to construct the Co(OH)〈sub〉2〈/sub〉/BP interfaces. Owing to the high Fermi level of Co(OH)〈sub〉2〈/sub〉 than that of BP, the electrons are transferred initiatively from Co(OH)〈sub〉2〈/sub〉 to BP, affording remarkable oxygen evolution reaction performance with an overpotential of 276 mV at a current density of 10 mA cm〈sup〉−2〈/sup〉. Moreover, the potentiostatic tests present decent electrocatalytic stability of the synthesized Co(OH)〈sub〉2〈/sub〉/BP nanosheets. It is further anticipated that engineering the interface towards manipulating the charge density on BP surface and/or interface by depositing other kind of catalysts could be a straightforward strategy to design outstanding hybrid electrocatalysts.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618326550-fx1.jpg" width="227" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Sun Jie, Ming Ting-yun, Qian Hui-xuan, Li Qi-song〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, copper-tin (Cu-Sn) alloy coating was prepared in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) using electrodeposition method. The electrochemical behaviors of different electrolytes and the electrodeposition reversibility of Cu-Sn alloy were studied using cyclic voltammetry (CV). The electro-crystallization mechanism was investigated using chronoamperometry at different step potentials on glassy carbon (GC) electrode. The micromorphology and phase composition of Cu-Sn alloy coatings were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed a new reduction peak located at −0.50 ∼ −1.00 V, which belonged to Cu-Sn co-deposition. The reduction of Cu-Sn alloy in this system was an irreversible process. The electro-crystallization of Cu-Sn alloy followed the three-dimensional instantaneous nucleation. The results for micro-morphologies showed that, when the potential is changed, different microstructures can be formed, whereas the morphology changed from snow-like to cypress leaf-like shape. The results for phase composition showed that Cu-Sn alloy coating at different electrodeposition potentials consisted of pure cubic system Cu〈sub〉13.7〈/sub〉Sn phase. Additionally, the Cu-Sn alloy deposition from [BMIM]Cl system showed a preferred orientation on (220) crystallographic plane, which is different from the standard card.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 296〈/p〉 〈p〉Author(s): G.B. Melle, E.G. Machado, L.H. Mascaro, E. Sitta〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The search for greener energy sources has led to the development of biodiesel. One of its by-product, glycerol, is usually converted into more valuable products by organic synthesis or homogeneous catalysis. There is still room for the research on converting this molecule by means of an electrolytic or fuel cell - for that goal, a deeper understanding of the process and its variables is desirable. This work aims at describing the role of mass transport at the glycerol electro-oxidation on polycrystalline platinum in acidic media. We found that at a proper condition, a new faradaic process is observable in the cyclic voltammetry at ∼0.55 V, regarding the oxidation of glycerol at lower potentials. By means of a numerical experiment it is proposed that a soluble intermediate, namely glyceraldehyde, is the main actor in the inhibition of the process and that its removal, by the electrode rotation, yields a less poisoned surface. The results presented suggest that the aim for electrolytic or fuel cells should be the development of catalysts less active for glyceraldehyde and that the mass transport is a key factor in designing those devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Weilu Yang, Minghua Zhou, Nihal Oturan, Yawei Li, Pei Su, Mehmet A. Oturan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Degradation of the herbicide 2,4-dichlorophenoxiacetic acid (2,4-D) in aqueous solutions has been studied by electrochemical oxidation process using N-doped graphene modified graphite felt cathode with ammonium nitrate as nitrogen source. The graphene was obtained via electrochemically exfoliated method (EEGr). Different ratios of EEGr/ammonium nitrate (1:0, 1:1, 1:3, 1:7) modified cathodes (N0-EEGr-GF, N1-EEGr-GF, N3-EEGr-GF, N7-EEGr-GF) were explored with electrochemical characterizations, and it was verified that N1-EEGr had the most significant catalytic performance for accelerating the activation of in-situ generated H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 into hydroxyl radicals. The effects of operating parameters such as applied potential, solution pH and initial concentration of 2,4-D on the degradation efficiency with N1-EEGr-GF were investigated. A fairly high mineralization rate (88%) was attained at pH 7 after 480 min electrolysis of 20 mg L〈sup〉−1〈/sup〉2,4-D solution. The N-doped graphene as catalyst was found to be more efficient in degradation performance compared with the unmodified graphite felt cathode. The electrochemical advanced oxidation process using this modified cathode allows extension of the working pH range compared to electro-Fenton process which is optimal at pH 3. Finally, a plausible pathway for 2,4-D mineralization was proposed according to the identified intermediated products.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S001346861832680X-egi10N9VHGBJWS.jpg" width="276" alt="Image 109" title="Image 109"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Ze Chai, Chuanhai Jiang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The corrosion behavior of Ni〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Co〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Cu nanocrystalline coatings in neutral salt environments was systematically investigated by potentiodynamic polarization, linear polarization, electrochemical impedance spectroscopy, and long-term salt spray tests. The electrodeposited ternary coatings were Ni-based solid solution alloys that contained markedly different contents of Co and Cu. Greater Co and Cu contents strongly reduced the polarization and charge-transfer resistance of the coatings, thus decreasing their corrosion resistance in neutral NaCl solutions. In salt spray tests, the initial porous corrosion product film on the Co-/Cu-poor coating evolved into a compact film that finally grew to cover the coating surface, while such morphological transition was absent on the Co-/Cu-rich coating, where the formed film showed a continuous deterioration in its initial porous structure. Abundant Co-/Cu-substituted α-Ni(OH)〈sub〉2〈/sub〉 might grow to form the primary compact films that could coalesce and thicken as corrosion was suppressed. A large amount of Cu(OH)〈sub〉2〈/sub〉 together with high corrosion rates might be detrimental to the formation of compact films. A mechanism of the formation of the corrosion product films was proposed based on the corrosion characteristics of the ternary system and detailed corrosion product film analysis.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Katerina Govatsi, Andreas Seferlis, Spyros N. Yannopoulos, Stylianos G. Neophytides〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present study, based on potentiodynamic and potentiostatic measurements as well on specific surface area analysis data we present a detailed study on the photoelectrochemical properties of ZnO nanorod (NR) arrays aiming to shed light on the photo-electrokinetics of oxygen evolution reaction (OER) on the ZnO surface interfaced with 0.1 M NaOH aqueous solution. The faradaic selectivity for the oxygen evolution is around 70% and takes place on the side-wall (e.g. 110) planes of the NRs, while H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 is produced on the (001) polar planes, which appear to be 3–4 times more reactive than the side-wall (110) planes. By the use and the kinetic analysis of potentiodynamic experiments it has been inferred that the OER mechanism involves two active sites on the (110) surface: (I) the surface Zn atoms where OH〈sup〉−〈/sup〉 are being discharged and adsorbed electrochemically 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mi〉O〈/mi〉〈msubsup〉〈mrow〉〈mi〉H〈/mi〉〈/mrow〉〈mrow〉〈mi〉a〈/mi〉〈mi〉d〈/mi〉〈/mrow〉〈mrow〉〈mi〉Z〈/mi〉〈mi〉n〈/mi〉〈/mrow〉〈/msubsup〉〈/mrow〉〈/math〉 and (II) the photo-induced oxygen vacancies where the former species migrate and are adsorbed as 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.gif" overflow="scroll"〉〈mrow〉〈mi〉O〈/mi〉〈msubsup〉〈mrow〉〈mi〉H〈/mi〉〈/mrow〉〈mrow〉〈mi〉a〈/mi〉〈mi〉d〈/mi〉〈/mrow〉〈mrow〉〈mi〉V〈/mi〉〈/mrow〉〈/msubsup〉〈/mrow〉〈/math〉 and evolved as O〈sub〉2〈/sub〉 under the effect of incident radiation. The transient kinetic analysis of the potentiodynamic measurements resulted in the determination of the electrokinetic parameters (Tafel slope 〈em〉(b)〈/em〉, symmetry factors 〈em〉(β)〈/em〉 and exchange current densities 〈em〉(I〈/em〉〈sub〉〈em〉o〈/em〉〈/sub〉〈em〉)〈/em〉) of the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mi〉O〈/mi〉〈msubsup〉〈mrow〉〈mi〉H〈/mi〉〈/mrow〉〈mrow〉〈mi〉a〈/mi〉〈mi〉d〈/mi〉〈/mrow〉〈mrow〉〈mi〉Z〈/mi〉〈mi〉n〈/mi〉〈/mrow〉〈/msubsup〉〈/mrow〉〈/math〉 and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.gif" overflow="scroll"〉〈mrow〉〈mi〉O〈/mi〉〈msubsup〉〈mrow〉〈mi〉H〈/mi〉〈/mrow〉〈mrow〉〈mi〉a〈/mi〉〈mi〉d〈/mi〉〈/mrow〉〈mrow〉〈mi〉V〈/mi〉〈/mrow〉〈/msubsup〉〈/mrow〉〈/math〉 species, thus providing significant insight as of their binding energies and their reactivity on the ZnO surface. The turnover frequency at the maximum of the applied bias photoconversion efficiency (ABPE) for the production of one molecule of O〈sub〉2〈/sub〉 is 0.35 s〈sup〉−1〈/sup〉.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618327890-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Yaqin Zhao, Xiaofang Cui, Jing yang, Lu Yu, Binsheng Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The interaction of 〈em〉Yersinia pestis〈/em〉 (YpHmuT) with Fe center on hemin (ferric form) or heme (ferrous form) was investigated by differential pulse voltammetry (DPV), cyclic voltammetry (CV), square wave voltammograms (SWV), electrochemical impedance spectroscopy (EIS) and spectra. Electrochemical signals of hemin/heme were strongly influenced by virtue of interacting with YpHmuT. The 2:1 stoichiometric ratio of the hemin or heme to YpHmuT was confirmed. YpHmuT binds to ferric hemin with pentacoordinate and high-spin and binds to ferrous heme with low-spin. Our findings may provide useful data for understanding biological processes of hemin transportation in 〈em〉Yersinia pestis〈/em〉.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Square wave voltammograms of hemin〈sub〉2〈/sub〉-YpHmuT (a) and heme〈sub〉2〈/sub〉-YpHmuT (b). Hemin〈sub〉2〈/sub〉-YpHmuT: green: YpHmuT backbone (PDB: 〈a href="http://www.rcsb.org/pdb/explore.do?structureId=3NU1" target="_blank"〉3NU1〈/a〉), red: hemin a, blue: hemin b; Heme〈sub〉2〈/sub〉-YpHmuT: green: YpHmuT backbone (PDB: 〈a href="http://www.rcsb.org/pdb/explore.do?structureId=3NU1" target="_blank"〉3NU1〈/a〉), orange: heme a, pink: heme b.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618328196-fx1.jpg" width="257" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Qian Lu, Yang Sun, Kaiming Liao, Xiaohong Zou, Ikutaro Hamada, Wei Zhou, Meng Ni, Zongping Shao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Poor electrical conductivity of sulfur, sluggish redox kinetics, dissolution of intermediate polysulfides, and expansion in volume upon cycling are the main drawbacks that hamper the practical application of Li-S batteries. By taking advantages of the high conductivity and favorable catalytic activity of RuO〈sub〉2〈/sub〉, we design a 3D carbon nanotube film with embedded RuO〈sub〉2〈/sub〉 nanoparticles as a freestanding type of chemisorptive and catalyst-like cathode for Li-S batteries, which can be facilely prepared by a surfactant-assisted vacuum infiltration method. Both experimental and theoretical results reveal the excellent capability of RuO〈sub〉2〈/sub〉 for anchoring polysulfides and accelerating the kinetics of polysulfides catalytic redox reactions. Besides, the 3D freestanding cathode is beneficial to overcoming pulverization during volume changes, especially for long-term cycling. At a high areal sulfur loading of 2 mg cm〈sup〉−2〈/sup〉, favorable initial capacities of 750 and 1060 mA h g〈sup〉−1〈/sup〉 respectively at 2 and 0.5 C are achieved. More attractively, the capacity after 1000 cycles maintains 405 mA h g〈sup〉−1〈/sup〉 at 0.5 C with a loss in capacity of only 0.06% per cycle. Additionally, such freestanding cathode allows the batteries to be tested under various bending stages, hence encouraging more research works on fabrication of other 3D nanostructure families as high-performance cathodes for Li-S batteries.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈strong〉A 3D free-standing catalyst-like cathode〈/strong〉 is designed and prepared for Li-S battery through a surfactant-assisted infiltration approach. Favorable high-rate performances and stabilities are delivered for Li-S battery with the as-prepared cathode due to the excellent chemisorption, high conductivity and for various redox reactions of RuO〈sub〉2〈/sub〉. The 3D free-standing catalyst-like cathode provides an inspirational model for promising flexible energy storage devices.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618328214-fx1.jpg" width="249" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Kané Rabé, Lifen Liu, Noor Ahmed Nahyoon, Yizhen Zhang, Ahmed Mahmoud Idris〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Degradation of pollutants can be integrated with electricity generation in Photocatalytic fuel cell under light irradiation or self-powered fuel cell in the dark. In fuel cell driven by electrode reactions, the electrode reduction and oxidation transforms chemical energy in pollutants into electrical energy. In this work, Rhodamine B and coking wastewater were treated, using an efficient Z-scheme g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉/Fe〈sup〉0〈/sup〉(1%)/TiO〈sub〉2〈/sub〉 as an anodic catalyst and WO〈sub〉3〈/sub〉 as a cathodic catalyst. After 100 min of reaction in a single chamber fuel cell with 10 Ω of external resistance, in 0.05 M Na〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 electrolyte, the paired stainless-steel electrodes loaded respectively with g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉/Fe〈sup〉0〈/sup〉(1%)/TiO〈sub〉2〈/sub〉 and WO〈sub〉3〈/sub〉, degraded 98% Rhodamine B and generated 0.95 V cell voltage under 50 W visible-light irradiation, while removed 60% RhB and generated 0.5 V without light. To investigate the PFC performance of g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉/Fe〈sup〉0〈/sup〉(1%)/TiO〈sub〉2〈/sub〉 in treating real coking wastewater, at optimal pH 2, 91% chemical oxygen demand (COD) and 89% total organic carbon (TOC) were removed and generated 0.3 V cell voltage. The influence of pH on photocatalytic degradation performance and cell voltage are evaluated. The high cell voltage is attributed to the very low impedance of the g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉/Fe〈sup〉0〈/sup〉(1%)/TiO〈sub〉2〈/sub〉 loaded anode. The excellent electrochemical properties of paired electrodes help in generating higher current density, due to the increased photocatalyst activity of the tridimensional catalyst as proved by electron spinning resonance spectrum, photoluminescence, and Electric Impedance Spectrum analysis.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618328317-fx1.jpg" width="345" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Xuemin Li, Andrew M. Colclasure, Donal P. Finegan, Dongsheng Ren, Ying Shi, Xuning Feng, Lei Cao, Yuan Yang, Kandler Smith〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Application of advanced anode and cathode materials in commercial lithium-ion batteries is attracting attention due to their high capacity. Silicon (Si)/graphite anodes and nickel (Ni)-rich lithium nickel manganese cobalt oxide with layered structures have been paired in commercial 18650 high energy density cells (∼270 Wh/kg). It is crucial to investigate the cell performance and the aging behavior of this commercial cell. In this study, we present commercial cell degradation mechanisms by comparing fresh and aged electrodes, including changes of crystal structure, morphology, elemental composition, and electrochemical properties. The quantitative analysis was done based on dV/dQ incremental capacity analysis of 18650 cells. To determine the amount of cyclable lithium ions (Li〈sup〉+〈/sup〉) and active material loss, the lithiation and delithiation capacity were compared for fresh and aged electrodes in half coin cells. Results showed that even with 5% (by mass) of Si added in the anode, cracks occurred across the anode leading to contact loss and thickening of the solid electrolyte interphase (SEI) layer. Additionally, the average fluorine (F) ratio of the aged anodes was higher compared to that of the fresh anodes. More severely, the F content on the Si aggregations on aged anodes increased to as high as 5 times that of the fresh anode, indicating SEI growth, especially on Si particles. Solid 〈sup〉7〈/sup〉Li nuclear magnetic resonance results showed no detectable Li metal deposition on the aged anode. On the cathode side, cracks on the primary particle interfaces contributed to cathode material loss, contact loss, and impedance rise. Therefore, Li〈sup〉+〈/sup〉 loss into the thickened SEI layer, particle cracking, and impedance rise are the main reasons behind cell degradation.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618326781-fx1.jpg" width="283" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Manavalan Vijayakumar, Duggirala Sri Rohita, Tata Narasinga Rao, Mani Karthik〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Smart adjustment of active mass loading on positive and negative electrodes, significant enhancement of energy density with long-term durability is achieved due to expand of operating potential window of the electrochemical capacitor. In the present contribution, two different carbon materials like indigenous activated carbon fibres and commercial Kuraray YP-50 carbon are utilised as electrodes and the equal/unequal mass configurations of electrochemical capacitor are systematically investigated by using 1 M tetraethylammonium tetrafluoroborate/AN as an organic electrolyte. The electrochemical performances of equal/unequal mass configurations are examined in terms of potential stability window and the durability of the electrochemical capacitor. The unequal mass configuration of carbon fibres electrodes shows 25% higher gravimetric energy density than unequal commercial YP-50 electrodes. Besides, unequal mass configuration of carbon fibres exhibit 41% higher gravimetric energy density as compared with commercial YP-50 carbon at 2.7 V as extensively reported in the literature. This result clearly explores the benefits of unequal mass configurations of electrochemical capacitor for extending the operation voltage window of organic electrolyte with long durability and this strategy enlightens the design of well-defined carbon-carbon based electrodes for commercial implementation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Megan Longstaff, Kaitlin Gardiner, Rodion Zhuravlev, Jacob Finney, Dean A. Waldow〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Block copolymers present the ability to design solid polymer electrolytes to include both ion conductivity and structural features which may lead to improved safety in lithium ion batteries. We report a morphology study of novel block copolymer electrolytes that were synthesized using ring opening metathesis polymerization. The monomers have an oxanorbornene dicarboximide backbone where the first block has oligomeric (n = 12) ethylene oxide (OEO) side chains and the second block has phenyl side groups. The former block achieves high salt solubility, while the latter block is a structural component with a high glass transition temperature. Block copolymers have been synthesized covering a range of compositions from 38 to 70 wt % of the phenyl containing block, and have been studied neat and with bis(trifluoromethane)sulfonimide lithium salt. The resulting morphologies were investigated using atomic force microscopy and small angle X-ray scattering (SAXS). Solvent vapor annealing was found to enhance ordering in the neat copolymer thin films and the addition of salt with solvent vapor annealing further increased long range order. Cylinder and lamellar structures dominate the observed morphologies and the addition of salt increases ordering and the range block copolymer compositions with lamellar structure. SAXS results demonstrate modest ordering, reinforce the observations from AFM, and show an increase in domain size with an increase in salt concentration.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Ling Cheng, Tao Jiang, Kai Yan, Jianyu Gong, Jingdong Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉When photoelectrocatalysis (PEC) couples with electroenzymatic catalysis (EEC), effective utilization of electrons from PEC process for yield of H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 plays an important role in the enzymatic catalysis. In the present work, we designed a novel dual-cathode PEC-EEC system for pollutant removal. In this system, BiVO〈sub〉4〈/sub〉 photoanode was prepared by electrodeposition for visible light-driven PEC process while carbon cloth was used as the first cathode for electrogeneration of H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 and hemin/Cu prepared by electrophoretic deposition acted as the second cathode for enzymatic catalysis. The performances of the constructed dual-cathode PEC-EEC system were evaluated by decoloring Rhodamine B (RhB), which showed high decoloration percentage with acceptable stability and reusability. Further, the system was applied to degradation of tetracycline (TC), indicating that about 93.6% of TC was removed after 2-h treatment. A pathway for TC degradation in such a dual-cathode PEC-EEC system was proposed based on the intermediates determined by liquid chromatography coupled to mass spectrometry in tandem (LC-ESI-MS/MS).〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618327932-fx1.jpg" width="265" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Bo Xu, Zaichun Liu, Weibin Qiu, Qian Liu, Xuping Sun, Guanwei Cui, Yuping Wu, Xiaoli Xiong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Identification of new effective and selective N〈sub〉2〈/sub〉 reduction electrocatalyst is still of critical importance for fundamental and application research. Here, we report La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanoplate performing as an efficient metal oxide catalyst for electrochemical N〈sub〉2〈/sub〉 fixation to NH〈sub〉3〈/sub〉, which exhibits excellent selectivity and stability with a high Faradaic efficiency of 4.76% and a NH〈sub〉3〈/sub〉 yield rate of 17.04 μg h〈sup〉−1〈/sup〉 mg〈sup〉−1〈/sup〉〈sub〉cat.〈/sub〉 at −0.8 V vs. reversible hydrogen electrode (RHE) in 0.1 M Na〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 solution under atmospheric pressure. Density functional theory (DFT) calculation results show that La atoms in La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 act as the active sites for efficiently adsorbing N〈sub〉2〈/sub〉. The optimal adsorption approach of N〈sub〉2〈/sub〉 molecule on the (011) face of La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 is end-on-two configuration which is highly activated. Thus La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 exhibits high performance for electrochemical reduction of N〈sub〉2〈/sub〉.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Liu-Liu Shen, Gui-Rong Zhang, Tizian Venter, Markus Biesalski, Bastian J.M. Etzold〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Paper-based microfluidic fuel cells emerge as a promising clean energy sources for small-scale electronic devices, while their broad-based applications require a comprehensive understanding of their structure-performance relationships. Here in this work, we made attempt to identify the key structural parameters that impact the overall performance of paper-based microfluidic fuel cells. The influences of fuel crossover, cell resistance, limitations from both anode and cathode, and in particular microfluidic paper channel properties have been systemically investigated and optimized towards the best practices. Among various structural parameters, we unravel for the first time that the overall performance of these paper-based microfluidic fuel cells is largely dependent on the textural properties of microfluidic paper channels. By correlating the fuel cell performance with the unambiguously determined flow rate of electrolyte within different paper channels, we found that a greater flow rate which was achieved by using paper with larger mean pore diameter, could result in higher peak power density and open circuit voltage. This performance enhancement would benefit from minimized reactant depletion near electrode surfaces and suppressed fuel crossover. Technically, an open circuit voltage of 0.86 V and a maximum power density of 7.10 mW/cm〈sup〉2〈/sup〉 can be achieved on a single cell (fuel: 4 M KCOOH; oxidant: air; electrolyte: 1 M KOH; catalyst: 0.2 mg/cm〈sup〉2〈/sup〉 Pd/C on 0.15 cm〈sup〉2〈/sup〉 graphite foil), and the maximum power output can be sustained for at least 1 h. The fuel cell power can also be easily increased proportionally when connecting two or more cells in series, which makes theses paper-based microfluidic fuel cells capable to power various electronic devices with different power requirements.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Julian Massing, Gerd Mutschke, Dominik Baczyzmalski, Syed Sahil Hossain, Xuegeng Yang, Kerstin Eckert, Christian Cierpka〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The origin of strong electrolyte flow during water electrolysis is investigated, that arises at the interface between electrolyte and hydrogen bubbles evolving at microelectrodes. This Marangoni convection was unveiled only recently (Yang et al., PCCP, 2018, [1]) and is supposed to be driven by shear stress at the gas-liquid interface caused by thermal and concentration gradients. The present work firstly allows a quantification of the thermocapillary effect and discusses further contributions to the Marangoni convection which may arise also from the electrocapillary effect. Hydrogen gas bubbles were electrolytically generated at a horizontal Pt microelectrode in a 1 M H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 solution. Simultaneous measurements of the velocity and the temperature field of the electrolyte close to the bubble interface were performed by means of particle tracking velocimetry and luminescent lifetime imaging. Additionally, corresponding numerical simulations of the temperature distribution in the cell and the electrolyte flow resulting from thermocapillary stress only were performed. The results confirm significant Ohmic heating near the micro-electrode and a strong flow driven along the interface away from the microelectrode. The results further show an excellent match between simulation and experiment for both the velocity and the temperature field within the wedge-like electrolyte volume at the bubble foot close to the electrode, thus indicating the thermocapillary effect as the major driving mechanism of the convection. Further away from the microelectrode, but still below the bubble equator, however, quantitative differences between experiment and simulation appear in the velocity field, whereas the temperature gradient still matches well. Thus, additional effects must act on the interface, which are not yet included in the present simulation. The detailed discussion tends to rule out solution-based effects, generally referred to as solutal effects, whereas electrocapillary effects are likely to play a role. Finally, the thermocapillary effect is found to exert a force on the bubble which is retarding its departure from the electrode.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Qianhao Geng, Guangxu Huang, Yingbin Liu, Yuanyuan Li, Longhui Liu, Xiaohui Yang, Qi Wang, Chuanxiang Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, we report a facile method for preparing the B/N co-doped 2D porous carbon nanosheets (BNHCs) with high contents of boron (3.41–3.96 at.%) and nitrogen (5.1–6.09 at.%) via annealing the mixtures of ammonium humate and H〈sub〉3〈/sub〉BO〈sub〉3〈/sub〉. The ammonium humate is used as nitrogen-containing carbon precursor, and H〈sub〉3〈/sub〉BO〈sub〉3〈/sub〉 acts as boron source and pore-forming agent. Moreover, we demonstrate firstly that the existence of H〈sub〉3〈/sub〉BO〈sub〉3〈/sub〉 can enhance the graphitization degree of BNHCs by inducing the conversion of BCO〈sub〉2〈/sub〉 to BC〈sub〉3〈/sub〉 with increasing the H〈sub〉3〈/sub〉BO〈sub〉3〈/sub〉/ammonium humate mass ratio to 2. BNHC-1.5 exhibits the highest specific surface area of 592 m〈sup〉2〈/sup〉 g〈sup〉−1〈/sup〉 among all the samples, and BNHC-2 shows the enhanced graphitization degree and highest mesopore ratio (60.5%). In a three-electrode system, the BNHC-1, BNHC-1.5 and BNHC-2 exhibit high specific capacitances of 305 F g〈sup〉−1〈/sup〉, 311 F g〈sup〉−1〈/sup〉 and 225 F g〈sup〉−1〈/sup〉 at 0.2 A g〈sup〉−1〈/sup〉, and 64 F g〈sup〉−1〈/sup〉, 125 F g〈sup〉−1〈/sup〉 and 120 F g〈sup〉−1〈/sup〉 at ultrahigh current density of 100 A g〈sup〉−1〈/sup〉, respectively. Moreover, as assembled symmetric supercapacitor electrodes with high active material mass loading (∼180 μm, ∼13 mg cm〈sup〉−2〈/sup〉), BNHCs deliver high specific capacitances of 170–210 F g〈sup〉−1〈/sup〉 at 0.05 A g〈sup〉−1〈/sup〉, and BNHC-2 presents an outstanding cyclic stability (94.8% capacitance retention after 10,000 cycles), making them promising candidates for practical supercapacitor application.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618327361-fx1.jpg" width="261" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Mark E. Orazem, Sanjeev Mukerjee, Plamen Atanassov〈/p〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Meichen Guo, Yao Li, Lingxi Zhou, Qiaoji Zheng, Wenjing Jie, Fengyu Xie, Chenggang Xu, Dunmin Lin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉It is of great significance to develop high-efficiency and low-cost electrocatalysts towards oxygen evolution reaction (OER) due to their critical role in the electrochemical water splitting to produce H〈sub〉2〈/sub〉 fuel. Herein, a well-controlled hierarchical structured bimetallic electrocatalyst of Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@Ni〈sub〉2〈/sub〉P-CoP/NF is constructed via phosphating and carbonating Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanowires template-directed fabrication Ni-substituted ZIF-67 arrays onto a 3D Ni foam substrate. The as-obtained hierarchical structured nanomaterial displays superior electrocatalytic performance with a small overpotential of 298 mV required to achieve the current density of 50 mA cm〈sup〉−2〈/sup〉 and reveals high electrocatalytic activity with long-term durability after continuously working for 40 h in 1.0 M KOH. The good performance of the material for OER can be attributed to the synergistic effect of optimized hierarchical structure, partial substitution of Ni for Co, high porosity and N, P-codoping.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Shan Zhao, Weidong Huang, Zisheng Guan, Biao Jin, Debao Xiao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electrochromism and related devices have been studied for a few decades from both fundamental and technological point of view. At the present stage, screening electrochromic materials with excellent properties is still an interesting job. In our previous work, we have demonstrated that hydroxyalkyl viologens could exhibit satisfying electrochromic behavior. Further, in this paper, the bis(dihydroxyalkyl) viologen, (1,1‘-bis(2,3-dihydroxypropyl) 4,4‘-bipyridine derivative dichloride, DHPV〈sup〉2+〈/sup〉2Cl〈sup〉-〈/sup〉, was synthesized and incorporated as an electrochromic chromophore in the all-in-one electrochromic devices (ECDs) on the basis of poly (vinyl butyal) (PVB)-carbonate and poły (vinyl alcohol) (PVA)-borax gel electrolytes, respectively. It was found that DHPV〈sup〉2+〈/sup〉 2Cl〈sup〉-〈/sup〉 in PVB-based gel ECDs underwent reversible switching between transparent and deep blue hue, whereas the clear color changes from colorlessness to amaranth in PVA-borax-based ones upon the potential ranges from 0 V to −1.0 V. For PVB-based gel ECD, spectroelectrochemical studies demonstrated that it only needs a low coloration voltage down to −0.6 V, and exhibites high coloration efficiency (η) up to 301 cm〈sup〉2〈/sup〉/C. The optical contrast of it only reduces by 1% after consecutive operation for 10000 cycles between −1.0 V and 0 V, demonstrating an excellent cycling stability of this kind of device. The ECD based on PVA-borax gel modified with glycerol shows burgundy, and good electrochromic performance. It is interesting to note that a relatively large-area PVB-based gel electrochromic devices up to 168 cm〈sup〉2〈/sup〉 was realized, the driving voltage and response time being −1.5 V and 12 s, respectively, for blue-violet coloration state. The advantages of electrochromic properties exhibited by 1,1‘-bis(2,3-dihydroxypropyl) viologen dichloride over those reported can be regarded as a pronounced improvement for organic electrochromic materials, and are expected to set the stage for novel electrochromic devices such as smart window and display applications and so forth.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Yi-Yang Zhang, Shao-Jian Zhang, Jun-Tao Li, Kai Wang, Yi-Cheng Zhang, Qian Liu, Rong-Shun Xie, Yi-Ru Pei, Ling Huang, Shi-Gang Sun〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉P2-type Mn-based cathode materials present high reversible capacities and low cost, but still suffer the poor cycle ability. In this study, a water-stable cathode material was synthesized by simple solid-state method, and kinds of water-soluble natural biopolymers including guar gum, sodium alginate and xanthan gum were investigated as the binder for this typical P2-type cathode material. As the water-soluble binders contain a large amount of 〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉OH and 〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉COO〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉 functional groups, they could result high adhesion between the particles and conductor, thus lead to a better conductivity. Indeed, an enhanced electrochemical performance was observed on these water-soluble binder, comparing with the commercialized PVDF binder. Among them, the P2-type cathode material with xanthan gum binder delivers the most significant improvement in cycling performance with the capacity retention of 77.6% at 40 mA g〈sup〉−1〈/sup〉 and 66% at 100 mA g〈sup〉−1〈/sup〉 after 80 and 200 cycle. The XPS depth profiles demonstrated that the dissolution of transition metal in this cathode materials, which lead to severe structural deformation and capacity fading during the repeated cycles, can be significant suppressed by the usage of the water-soluble binders.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Pengfei Zhang, Chen Chen, Xiaohua Zhang, Zhigang Jiang, Junlin Huang, Jinhua Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉N-enriched porous carbon materials represent a kind of effective electrocatalysts for oxygen reduction reaction (ORR), which have received extensive attention owing to their low-cost, advantageous catalytic activity and stability. However, exploring non-noble-metal catalysts for replacing high-cost notable metal catalysts remains a major challenge. Herein, iron and sulfur co-doped N-enriched hierarchical porous carbon polyhedron (NC) derived from metal-organic framework (Fe/S-NC) was successfully prepared by a facile strategy, including a direct pyrolyzation of zeolitic imidazolium framework (ZIF-8) and a further pyrolysis of the impregnated NC with Fe(SCN)〈sub〉3〈/sub〉 solution. Electron microscopic studies showed that Fe/S co-doping has not changed the polyhedron morphology of NC. The resulted Fe/S-NC demonstrated obviously enhanced ORR activity, excellent durability and methanol tolerance in both alkaline and acidic media. The half-wave potential of the Fe/S-NC exhibited 32 mV positive shift in 0.1 M KOH, and only 25 mV negative shift in 0.5 M H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉, respectively, as compared to that of the commercial Pt/C (20% Pt loading) catalyst. The superior performance is attributable to the combined roles of the unique hierarchical porous structure of NC and the Fe/S co-doping by endowing Fe/S-NC with great specific surface area, rich active sites, excellent conductivity and synergistic effect between Fe-N〈sub〉x〈/sub〉-C active sites and a thiophene-like structure (C-S-C).〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Iron and sulfur co-doped N-enriched hierarchical porous carbon derived from metal-organic framework (Fe/S-NC) exhibit more prominent ORR activity and superior durability and methanol tolerance as compared to Pt/C in both alkaline and acidic media.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618328299-egi10XWVGMT8V6.jpg" width="351" alt="Image 1086" title="Image 1086"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Qingyang Yu, Shuai Yin, Jian Zhang, Huiming Yin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nanoporous gold (NPG) with three-dimensional bi-continuous structure have attracted many attentions ascribed to their desirable material characteristics, such as high surface area, high conductivity and outstanding chemical stability, especially for electrocatalysis. NPG-based electrocatalysts have exhibited notable properties towards oxygen reduction reaction (ORR), methanol oxidation reaction, formic acid oxidation reaction and related polymer electrolyte membrane fuel cells. In this work, structure dependent activity and durability towards ORR on NPG supported Pt (NPG-Pt) were investigated, because of the key roles of ORR in various applications such as fuel cell, metal-air batteries and H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 generations. Typical NPG-Pt electrocatalysts with epitaxially monolayer, two-layer Pt shells and Pt nanoparticles were selected and systematically investigated relative to commercial Pt/C (20%, JM). The results reveal that all the NPG-Pt catalysts even the sample with only monolayer Pt i.e. Pt loading of 1.1 μg cm〈sup〉−2〈/sup〉 mainly exhibit 4-electron ORR pathway without any H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 yield, while commercial Pt/C with loadings lower than 2.4 μg cm〈sup〉−2〈/sup〉 will favor H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 generation which is harmful for the long-term stability. According to the performance stability, conventional accelerated degradation tests reveal that NPG-Pt with two-layer Pt shell (NPG-Pt〈sub〉2〈/sub〉) exhibits the best stability ascribed to the strong metallic bond between Au and Pt. The mass ORR activity of this catalyst is almost unchanged (∼2% reduction) after 30000 cycles potential sweeping while the mass ORR activity of Pt/C with Pt loading of 20 μg cm〈sup〉−2〈/sup〉 loses ∼60%. Therefore, NPG-based electrocatalysts present a good activity and stability than common nanoparticle electrocatalysts and developing nanoporous structure but cheap metal based electrocatalysts is a perspective way for cost reduction for commercial applications in energy storage and conversion field.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Jae-Hoon Hwang, Xiaochen Wang, Daoli Zhao, Matthew M. Rex, Hyoung J. Cho, Woo Hyoung Lee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel modified nanoporous bismuth electrode (modified-NPBiE) sensor was prepared by consecutive procedures which consist of bismuth (Bi) and tin (Sn) electroplating, thermal treatment for alloying Bi-Sn film, and selective chemical dealloying of Sn. The newly prepared modified-NPBiE sensor exhibited improved lifetime (2.7 times longer than a conventional nanoporous Bi-filmed electrode with over 40 repeated measurements) sensor with lower relative standard deviation (RSD), indicating enhanced stability and reproducibility for heavy metal detection. Using square wave anodic stripping voltammetry (SWASV), two noticeable peaks were observed at −0.65 V and −0.45 V associated with stripping currents of Cd〈sup〉2+〈/sup〉 and Pb〈sup〉2+〈/sup〉 in 0.1 M acetate buffer solution at pH 4.6, respectively. The calibration curves showed strong correlations with respect to various concentrations of Cd〈sup〉2+〈/sup〉 and Pb〈sup〉2+〈/sup〉 with the limit of detection (LOD) of 1.3 ppb for Cd〈sup〉2+〈/sup〉 and 1.5 ppb for Pb〈sup〉2+〈/sup〉. The newly modified-NPBiE sensor was then successfully applied for detecting Cd〈sup〉2+〈/sup〉 and Pb〈sup〉2+〈/sup〉 in a tap water environment and exhibited an acceptable performance for measuring heavy metals with a good reliability.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618328329-fx1.jpg" width="303" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Wanchen Wu, Jianfeng Huang, Jiayin Li, Lei Zhou, Liyun Cao, Yayi Cheng, Yuanyuan He, Qianying Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Controlling the growth of (001) lattice plane for orthorhombic niobium pentoxide is an effective method to enhance its electrochemical performance. Herein, the oriented Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉@C nanorods with capsule structure which grows along the perpendicular direction to the (001) lattice plane are successfully fabricated by a hydrothermal method with a later heat treatment process. As an anode for Li-ion batteries, the oriented Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉@C composite delivers an ultralong cycling stability of 200 mAh g〈sup〉−1〈/sup〉 after 1000 cycles at 5 A g〈sup〉−1〈/sup〉 and enhanced rate capability of 413 and 143 mAh g〈sup〉−1〈/sup〉 at 0.1 and 5 A g〈sup〉−1〈/sup〉 respectively, which are much better than those of Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 electrode. Further investigations reveal that the oriented Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉@C composite shows lower charge-transfer resistance, higher Li〈sup〉+〈/sup〉 diffusion coefficient and maintains a surface-controlled pseudocapacitive mechanism. The superior performances are ascribed to the synergetic effect of [001]-orientation, small Li〈sup〉+〈/sup〉 diffusion lengths in the nanorods building flowers and capsule-nanostructure with uniform carbon coating.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618328305-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Bryan Tang, Richard Gondosiswanto, David Brynn Hibbert, Chuan Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Non-volatile superbased-derived protic ionic liquids are thermally stable and highly conductive, thus hold great promises for electrochemical applications. However, systematic accounts of their electrochemical properties are yet to be established. In this contribution, five hydrophobic superbase-derived protic ionic liquids (PILs) have been prepared from Brønsted superbases and the salts of strong acids, and their decomposition temperature, density, conductivity and viscosity have been measured. The greatest viscosity was observed with the superbased PILs, [MTBDH][NfO] (2212 cP) and the least with [MTBDH][NTf〈sub〉2〈/sub〉] (121 cP). Greatest conductivity was measured for [MTBDH][NTf〈sub〉2〈/sub〉] (1.54 mS cm〈sup〉−1〈/sup〉) and the least for [MTBDH][NfO] (0.089 mS cm〈sup〉−1〈/sup〉). By combining density, conductivity and viscosity, a Walden plot was set up to demonstrate the degree of ionization, or ‘ionicity’ of each of the five PILs is greater than 10%. Their electrochemical characteristics were determined using cyclic voltammetry. Two IUPAC-recommended internal potential reference systems, ferrocene/ferrocenium and cobaltocenium/cobaltocene, were assessed for use in the five PILs. Potential windows of the five PILs were established at glassy carbon, gold and platinum electrodes, where the widest potential window was observed with glassy carbon electrodes with no direct correlation found between the Δp〈em〉K〈/em〉a values and the potential windows. The widest potential window was measured in [MTBH][beti] (4.3 ± 0.1 V) and the shortest in [HNC(dma)H][beti] (2.7 ± 0.1 V). The double layer capacitance was also investigated for potential applications in supercapacitors.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Willian G. Nunes, Leonardo M. Da Silva, Rafael Vicentini, Bruno G.A. Freitas, Lenon H. Costa, Aline M. Pascon, Hudson Zanin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report an electrode material for supercapacitors composed of nickel oxide (NiO) nanoparticles supported onto radially oriented multi-walled carbon nanotubes (CNTs) using a stainless-steel fine-mesh as the support (AISI:CNT-NiO). CNT scaffolds showed a turbostratic multi-walled structure with an interplanar spacing of 0.32 ± 0.02 nm and a diameter of ∼20–100 nm. NiO nanoparticles exhibited a diameter of ∼2–7 nm. X-ray data confirmed the presence of NiO in the scaffold. A large pseudocapacitive voltage range of 2.0 V was obtained in a 1.0 M Li〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 aqueous solution. The main contribution to the overall pseudocapacitance is due to the presence of reversible solid-state surface Faradaic reactions involving the Ni(II)/Ni(III) redox couple. High specific capacitance values of ∼1200 F g〈sup〉−1〈/sup〉 at 5 A g〈sup〉−1〈/sup〉 for the AISI:CNT-NiO electrode were extracted from galvanostatic discharge curves. Considering the contribution of negative voltages, the specific power and energy determined using cyclic voltammetry exhibited values of ∼140 Wh kg〈sup〉−1〈/sup〉 and ∼9 W kg〈sup〉−1〈/sup〉, respectively, at 0.02 V s〈sup〉−1〈/sup〉. A specific capacitance of ∼1028 F g〈sup〉−1〈/sup〉 was obtained at this scan rate. Even after 40,000 cycles carried out under galvanostatic conditions, the symmetric coin cell remained stable with a very high coulombic efficiency of ∼99%, which is a remarkable result. Also, we attributed to carbon nanotubes an extraordinary stability as electron drain on the current collector. The morphology factor analysis revealed that 19% of the electrochemically active surface area is confined to the inner surface regions of the porous nanostructured active layer. A low value of 0.15 mΩ g was extracted for the equivalent series resistance. New 〈em〉insights〈/em〉 are presented concerning the true meaning of negative voltages for coin cells. Interesting findings regarding the porous nature of electrodes were elucidated using the impedance technique.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Jiangnan Xing, Yang Li, Siwei Guo, Ting Jin, Haixia Li, Yijing Wang, Lifang Jiao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Developing low-cost and highly efficient electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is attractive for overall water splitting. Herein, we firstly use the globally generated green cornstalks as the carbon source to prepare highly efficient bifunctional pure β-phase molybdenum carbide (β-Mo〈sub〉2〈/sub〉C) electrocatalysts. Due to the highly intrinsic activity of β-Mo〈sub〉2〈/sub〉C, high porosity of the resultant and synergistic effect between the Mo〈sub〉2〈/sub〉C and carbon matrix, the as-prepared catalyst exhibits excellent electrocatalytic activities with low overpotentials of 130 mV and 274 mV to achieve a current density of 10 mA cm〈sup〉−2〈/sup〉 for the HER and OER, respectively. As a bifunctional electrocatalyst for overall water splitting, the electrolyzer only needs a cell voltage of 1.65 V at 10 mA cm〈sup〉−2〈/sup〉 in alkaline water, as well as long-term stability of 30 h. This intriguing preparation strategy will open up an exciting new avenue for the synthesis of other carbides.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Wushuang Chen, Xu Yu, Zhixin Zhao, Sucheng Ji, Ligang Feng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A hierarchical architecture of coupling graphene and 2D WS〈sub〉2〈/sub〉 for high-performance supercapacitors is fabricated by a facile ice-template approach. The hybridization content of WS〈sub〉2〈/sub〉 in graphene architecture strongly affects the morphology structure and surface chemical nature of the electrode, and can significantly enhance electrochemical behaviors. As proposed, the hierarchical WS〈sub〉2〈/sub〉/graphene architectures (WGA) showing rough and wrinkled surface can facilitate electrolyte diffusion and increase the wettability during the measurement. Meanwhile, the formation of 1T WS〈sub〉2〈/sub〉 and covalent bonds at WS〈sub〉2〈/sub〉/graphene interface are component for the improvement of pseudocapacitive behavior of WGA; A high performance like a superior specific capacitance (383.6 F g〈sup〉−1〈/sup〉), good rate capability (79.9%) and excellent cyclic stability (102.5%) is found due to the fast proton insertion into the WS〈sub〉2〈/sub〉 nanoflakes. This work provides an efficient and facile strategy to construct the hierarchical architectures for pseudocapacitive capacitors.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618328032-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Vuslat Buk, Martyn E. Pemble〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A miniaturised biosensor for glucose was prepared by immobilizing glucose oxidase (GOx) onto a carbon quantum dots (CQDs)-gold nanoparticles (AuNPs) nanohybrid material which was in turn attached to gold micro disk array electrodes. The gold micro disk array electrodes (GDAE) were microfabricated on Si substrate using electronics-standard lithography, deposition and etching techniques. Each microelectrode consisted of 85 gold disk electrodes with 20 μm diameter and 200 μm inter-electrode distance and were located hexagonally. The electrodes were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM) and cyclic voltammetry (CV). CV of the bare electrodes showed a symmetrical sigmoidal voltammogram arising from their radial diffusion profile. The electrodes developed were used to fabricate a miniaturised glucose biosensor. The resulting biosensor exhibited a high sensitivity of 626.06 μA mM〈sup〉−1〈/sup〉 cm〈sup〉−2〈/sup〉 towards glucose detection with excellent reproducibility and reusability. The superior performance of the biosensor is discussed in relation to the use of the micron-sized low density disk array electrodes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Note that the sizes of the components shown are not drawn to scale.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S001346861832766X-fx1.jpg" width="374" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Maozhan Huang, Zhou Xu, Cheng Hou, Shiqin Wang, Yan Zhuang, Hai-lang Jia, Mingyun Guan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Co-substituted Ni(OH)〈sub〉2〈/sub〉/carbon nanofiber (CNF) composite was synthesized by chemical coprecipitation method. X-ray powder diffraction (XRD) patterns evidenced that it was an intermediate phase with 〈em〉α-β〈/em〉 structure. Transmission electron microscopy (TEM) images suggested crystalline 〈em〉α-β-〈/em〉Ni〈sub〉x〈/sub〉Co〈sub〉1-x〈/sub〉(OH)〈sub〉2〈/sub〉 nanosheets growth on the surface of CNFs. The testing results of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and charge-discharge showed that the composites had high specific capacitances, low electrochemical reaction impedance, and long cycle stability. Using the composite as a cathodic active material, a specific capacity of assembled NiZn pouch cells ranged from 160.25 mAh·g〈sup〉−1〈/sup〉 at current density of 15 mA cm〈sup〉−2〈/sup〉 to 91.35 mAh·g〈sup〉−1〈/sup〉 at current density of 50 mA cm〈sup〉−2〈/sup〉. In addition, those NiZn pouch cells have excellent rate performance and long cycle stability. After 1500 cycles, the energy capacity retained 215.24 Wh·kg〈sup〉−1〈/sup〉, 98% of the initial value. The relationship between structure and the electrochemical performance was analyzed and discussed in detail. Intermediate phase 〈em〉α-β-〈/em〉Ni〈sub〉1-x〈/sub〉Co〈sub〉x〈/sub〉(OH)〈sub〉2〈/sub〉/CNF composites can be a promising cathodic active material for Ni-based batteries.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Zhi Deng, Jintao Gu, Yuyu Li, Shuai Li, Jian Peng, Xiang Li, Jiahuan Luo, Yangyang Huang, Chun Fang, Qing Li, Jiantao Han, Yunhui Huang, Yusheng Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Na〈sub〉2〈/sub〉Zn〈sub〉2〈/sub〉TeO〈sub〉6〈/sub〉 is a potential sodium solid electrolyte of all-solid-state sodium-ion batteries. In this work, Na〈sup〉+〈/sup〉 ion conductivity and electrochemical performance of layered Ca-doped Na〈sub〉2〈/sub〉Zn〈sub〉2-〈em〉x〈/em〉〈/sub〉Ca〈sub〉〈em〉x〈/em〉〈/sub〉TeO〈sub〉6〈/sub〉 (〈em〉x〈/em〉 = 0–0.05) (NZTO-C〈em〉x〈/em〉) electrolytes have been investigated. The highest conductivity has been achieved 7.54 × 10〈sup〉−4〈/sup〉 S cm〈sup〉−1〈/sup〉 in NZTO-Cx at 〈em〉x〈/em〉 = 0.02, at room temperature due to grain-boundary modification and interlayer-interface elimination. Meanwhile, chemical stability with metallic Na anode and electrochemical window of NZTO-C〈em〉x〈/em〉 are improved by Ca doping. Furthermore, the cycle stability of Na〈sub〉3〈/sub〉V〈sub〉2〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉3〈/sub〉/NZTO-C〈em〉x〈/em〉/Na solid-state batteries have been successfully increased by Ca doping. These advantages highly demonstrate good potential application prospect of NZTO-C〈em〉x〈/em〉 in all-solid-state sodium-ion batteries.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Umair Gulzar, Tao Li, Xue Bai, Subrahmanyam Goriparti, Rosaria Brescia, Claudio Capiglia, Remo Proietti Zaccaria〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Among various carbon materials, nitrogen doped single walled carbon nanohorns (N-SWCNHs) have a unique structure of clustered conical cages (2–5 nm in diameter and 40–50 nm in length) arranged in dahlia, bud and seed-like configurations. Each conical cage has five pentagons at their tips which act as potential reactive site with their own distinct chemistry. We exploited these reactive sites of N-SWCNHs by preferentially growing germanium nanocrystals (Ge NCs) onto their conical tips using oleylamine as a mild reducing agent. Therefore, Ge decorated N-SWCNHs (Ge@N-SWCNHs) composite was used, for the first time, as active anode material for lithium ion batteries providing high and stable capacity of 1285 mAh/g at 0.1C after 100 cycles. Our results show that preferential growth of Ge Nanocrystals (NCs) on the tips of N-SWCNHs not only allows high utilization of active material but prevents the aggregation of Ge NCs after multiple cycling. Finally, we highlight the potential role of N-SWCNHs as cheap and industrially scalable conductive host for next generation lithium ion batteries.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618326136-fx1.jpg" width="309" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Azam Khorasani, Maziar Marandi, Azam Iraji zad, Nima Taghavinia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this research a combinative electron transport layer (ETL) composed of TiO〈sub〉2〈/sub〉nanocrystals (NCs) and nanorods (NRs) were prepared and applied in perovskite solar cells (PSCs). TiO〈sub〉2〈/sub〉NCs with dominant size of 20 nm were synthesized through a hydrothermal method. TiO〈sub〉2〈/sub〉NRs were also grown through another hydrothermal process using P25 TiO〈sub〉2〈/sub〉nanoparticles (NPs) as the precursors. The diameter and length of the TiO〈sub〉2〈/sub〉NRs were measured about 80 nm and 1–2 μm, respectively. Different combinative pastes including TiO〈sub〉2〈/sub〉NCs and NRs were prepared and applied in ETL component of the PSCs. The weight percent (wt%) of the included TiO〈sub〉2〈/sub〉NRs in electron transport layer was altered in the range of 0–20%. A conventional structure of FTO/TiO〈sub〉2〈/sub〉compact layer/TiO〈sub〉2〈/sub〉NCs-NRs mesoporous layer/Perovskite/Spiro-OMeTAD/Au. was utilized for fabrication of PSCs in ambient condition. Cs〈sub〉0.05〈/sub〉(MA〈sub〉0.17〈/sub〉FA〈sub〉0.83〈/sub〉)〈sub〉0.95〈/sub〉Pb(I〈sub〉0.83〈/sub〉Br〈sub〉0.17〈/sub〉)〈sub〉3〈/sub〉mixed halides perovskite was also used due to its proper bandgap energy, crystalline quality and longtime stability. The effect of ETL composition i.e. the weight percent of the composing TiO〈sub〉2〈/sub〉NRs on the photovoltaic (PV) performance of the cells was investigated. According to the results, the PSC with a combinative ETL including 10 wt% of the TiO〈sub〉2〈/sub〉NRs demonstrated a J〈sub〉sc〈/sub〉 = 22.95 mA/cm〈sup〉2〈/sup〉, V〈sub〉oc〈/sub〉 = 1.055 V, FF = 0.71 and η = 17.2%. This energy conversion efficiency was increased about 20% compared to that of the PSC with nanocrystalline, NRs-free ETL. The reason was attributed to the optimized electron transport property of the ETL and crystalline quality of the over-grown perovskite layer.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618326537-egi1015C27W5X9.jpg" width="294" alt="Image 10152759" title="Image 10152759"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): D. Dixon, A. Schoekel, C. Roth〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉〈em〉In operando〈/em〉 Ru K edge X-ray absorption spectra were recorded at various cell voltages from specific regions of a direct methanol fuel cell (DMFC), such as methanol inlet, outlet and middle regions. From the linear combination fitting analysis, it was found that 50% of the Ru in the pristine Pt/Ru catalyst is in an oxidized form that matches with hydrated ruthenium oxide (RuO〈sub〉2〈/sub〉·xH〈sub〉2〈/sub〉O). During the DMFC cycling, fraction of this oxide phase gets reduced and forms metallic Ru. Furthermore, it is observed that under normal DMFC operation at various cell voltages relatively a higher amount of RuO〈sub〉2〈/sub〉 phase is present at the methanol inlet compared to the methanol outlet. This difference in the amount of RuO〈sub〉2〈/sub〉 phase observed translates into inhomogeneous distribution of potential/current within a single cell. The amount of RuO〈sub〉2〈/sub〉 phase increased further when the DMFC was subjected to fuel starvation conditions (very high anode potential). Again compared to the methanol outlet region, a higher amount of RuO〈sub〉2〈/sub〉 phase was found at the methanol inlet. As RuO〈sub〉2〈/sub〉 is more prone to dissolution compared to metallic Ru, it can be concluded that methanol inlet region is more prone to Ru dissolution compared to methanol outlet region.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Xinlu Li, Yin Liu, Xinlin Zhang, Cong Yao, Ronghua Wang, Chaohe Xu, Juan Lei〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A porous spherical hybrid of TiO〈sub〉2〈/sub〉 (B)/anatase entwined by graphene nanoribbons (GNRs) was synthesized by a facile and scalable method. The entwining of GNRs can adhere on the surface of TiO〈sub〉2〈/sub〉 by electrostatic interactions and prevent TiO〈sub〉2〈/sub〉 nanoribbons from self-scrolling to nanotubes, facilitating large lithium storage and high rate capability. The TiO〈sub〉2〈/sub〉/GNRs nanocomposite exhibited high rate capability in galvanostatic charge-discharge experiments, providing a capacity of 131 mAh g〈sup〉−1〈/sup〉 with a coulombic efficiency of 99.2% at a charge rate of 10C (1 C = 335 mA g〈sup〉−1〈/sup〉) over 1400 cycles. The appealing electrochemical performance can be attributed to the synergistic effect of TiO〈sub〉2〈/sub〉 nanoribbons entwined by GNRs.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618327257-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Zhenqi Cui, Jia Yao, Tao Mei, Shiyuan Zhou, Baofei Hou, Jing Li, Jinhua Li, Jianying Wang, Jingwen Qian, Xianbao Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In our study, TiC-TiO〈sub〉2〈/sub〉/S composite was successfully prepared with a simple and effective method. For this special micro-mesoporous structure, TiC-TiO〈sub〉2〈/sub〉 can be used as an efficient sulfur storing material, and also restrain the volume expansion of sulfur to a certain degree for its suitable specific surface area. TiO〈sub〉2〈/sub〉 and TiC can suppress the diffusion of polysulfides due to their strong interaction with polysulfides. At the same time, TiC also can remedy the nonconductive defect of sulfur for its good conductivity. With the help of above advantages, the TiC-TiO〈sub〉2〈/sub〉/S cathode delivers an initial discharge specific capacity of 1218 mAh g〈sup〉−1〈/sup〉 at 1 C (1 C = 1675 mA g〈sup〉−1〈/sup〉) with the sulfur loading of 1.5 mg cm〈sup〉−2〈/sup〉. And when cycles at 0.5 C, a stable capacity of 714 mAh g〈sup〉−1〈/sup〉 can be maintained after 500 cycles accompanied with the sulfur loading of 1.1 mg cm〈sup〉−2〈/sup〉.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Here a simple and effective method was designed to prepare 〈strong〉TiC-TiO〈/strong〉〈sub〉〈strong〉2〈/strong〉〈/sub〉〈strong〉/S composite〈/strong〉 to achieve the aim that stabilize and prolong the life of Li-S batteries with the synergistic effect by TiC and TiO〈sub〉2〈/sub〉. When served as the cathode for Li-S batteries, the TiC-TiO〈sub〉2〈/sub〉 composite exhibited strong chemisorption to lithium polysulfides, and the cell with TiC-TiO〈sub〉2〈/sub〉/S cathode delivered improved long life cyclability.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618327828-fx1.jpg" width="381" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Shaomei Cao, Liyi Shi, Miao Miao, Jianhui Fang, Hongbin Zhao, Xin Feng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this article, a flexible free-standing MoS〈sub〉2〈/sub〉 based paper-electrode for lithium-ion batteries (LIBs) was assembled according to a solution-based papermaking process and subsequent 〈em〉in situ〈/em〉 carbonization. The ultrathin MoS〈sub〉2〈/sub〉 nanosheets as active materials were efficiently exfoliated from bulk counterparts using TEMPO-oxidized cellulose nanofibrils (CNF) as assistant agents. Meanwhile, the oxidized CNF was utilized both as biobased binder and fibrous skeletons for the fabrication of hierarchical MoS〈sub〉2〈/sub〉 hybrid films. The MoS〈sub〉2〈/sub〉 based nanoarchitectures were finally achieved with carbon nanotubes (CNTs) as conductive fillers and further 〈em〉in situ〈/em〉 carbonized under argon atmospheres. The 〈em〉in situ〈/em〉 carbonization improved the electrical conductivity and specific surface area dramatically. The flexible paper-electrode assembled with ultrathin MoS〈sub〉2〈/sub〉 nanosheets, carbonized CNF (C-CNF) and CNTs exhibited enhanced performance with a high specific capacity, nice rate capability, and long time cycling stability. The carbonized MoS〈sub〉2〈/sub〉/CNF/CNTs hybrid film can directly act as an ideal paper-electrode for LIBs without using traditional metallic current collector makes it appropriate for the next-generation flexible/wearable electronics in future.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Carbonized MoS〈sub〉2〈/sub〉 nanosheets/cellulose nanofibrils hybrid films with enhanced conductivity can be directly used as ideal paper-electrode for LIBs without metallic current collectors.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618327658-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Na Li, Shoufeng Tang, Yandi Rao, Jinbang Qi, Qingrui Zhang, Deling Yuan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Photocatalytic fuel cell (PFC) is promising owing to its synchronous organic pollutants removal and energy recycle, but it still remains to improve in the cell performance. Herein, we demonstrate a synergistic method adding peroxymonosulfate (PMS) into PFC to promote antibiotic tetracycline (TC) degradation and simultaneous electric power generation. The introduction of PMS could be activated by the photoelectric effects, also used as the electrolyte and electron acceptor, which could enhance the photoelectrocatalysis and spread the reaction space from the electrode surface to the whole system. Herein, the PFC/PMS augmented the TC decontamination by 82.83% and electricity production by 122.40% versus the PFC without introducing PMS, respectively. In addition, factors controlled namely PMS dosage, solution pH, and UV intensity were investigated for the cell performance of the coupling system. Furthermore, UV–Vis spectrum and TOC analysis confirmed the destruction mineralization of TC. Moreover, a series of radicals quenching experiments were implemented to explore the cooperative elimination mechanism, and the results indicated that hydroxyl and sulfate radicals played the key roles at the acidic condition, and the direct oxidation of PMS dominated the chief effect at the neutral environment, and singlet oxygen and superoxide anion acted the primary function in the alkaline circumstance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Salahuddin Ahamad, Amit Gupta〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nano-conductive additives in composite electrodes play a significant role in influencing the electrochemical performance of the carbon anode in Li-ion batteries. These additives with a high electronic conductivity lead to the formation of a uniform solid-electrolyte interfacial layer, improved cycle life, and rate capability. In this work, the parameters that lead to such a performance improvement, namely the kinetic and transport properties, are carefully studied with carbon black (CB), carbon nanotubes (CNT) and a mixture of the two as conductive additives in mesocarbon microbeads (MCMB) anode. Experimental measurements indicate that the electrochemical reaction rate is controlled by interfacial kinetics up to moderately high C-rate (〈6C). Though nano-additives do not affect the solid phase diffusivity, the diffusion of Li-ion is considerably influenced by stages and their coexistence that is revealed through X-ray diffraction of cells at different depths of discharge. Using electrochemical impedance spectroscopy of half-cells cycled at different temperatures, the activation energy for charge transfer reaction and activation energy for SEI layer diffusion are estimated. The results exhibit an improvement in electron transfer and an ionically conducting SEI layer with the use of a mixture of CB and CNT as conductive additives. It is expected that the estimated kinetic and transport parameters and their temperature dependence for the additives under consideration will be of tremendous utility in the thermal, electrochemical, or aging modeling of batteries employing MCMB as anode material.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 297〈/p〉 〈p〉Author(s): Adebayo A. Adeniyi, Jeanet Conradie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Insight is provided into the reduction potential, p〈em〉K〈/em〉〈sub〉a〈/sub〉, energy of deprotonation and other electronic properties of eleven keto-enol tautomers of β-diketone derivatives, using density functional methods (DFT) and higher computational G3(MP2) methods. The computed reduction potential significantly reproduced the experimentally reported reduction potential values, with a mean absolute deviation (MAD) of 0.037 eV when using the higher computational G3(MP2) method, and a MAD of 0.061 eV when using the M06/6-311+G(df,p) DFT only method. Calculations proved a greater ease of reduction for the enol form of the β-diketones, indicated by higher (less negative) reduction potentials than their keto counterparts. The enol forms showed a further differentiation, with even higher reduction potentials observed when enolization occurred furthest from the more electron withdrawing side group. Latter enols also resulted in a lower dipole of the linking fragment between the electron donor and acceptor fragments (side groups). The computational results further provided more insight into the experimentally observed p〈em〉K〈/em〉〈sub〉a〈/sub〉 values, suggesting the possibility of proceeding by deprotonation of the hydroxy group from the enol form of the molecules, rather than their keto form. The strength of the O⋯H hydrogen bonds in the enol forms of the β-diketones increased for the enolization site closest to the more electron withdrawing side group and proved to be stronger in the β-diketones with a higher experimental p〈em〉K〈/em〉〈sub〉a〈/sub〉. The computed hyperpolarizability of β-diketones was found to be highly dependent on the position of enolization, increasing with a lower band gap, higher polarizabilities (Δα〈sub〉1〈/sub〉, Δα〈sub〉2〈/sub〉) and lower stability or higher aromaticity, in terms of the exaltation index (Γ).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Borong Wu, Jiaying Bi, Qi Liu, Daobin Mu, Lei Wang, Jiale Fu, Feng Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effect of different current density on the structure transformation of LiNi〈sub〉0.6〈/sub〉Co〈sub〉0.2〈/sub〉Mn〈sub〉0.2〈/sub〉O〈sub〉2〈/sub〉 material is studied under a cut-off voltage (4.6 V). It shows that the capacity fading is accelerated at the high discharge current density. It is mainly caused by the structure instability of the material. When the current density increases, the loss of lithium on the surface of the material becomes severe, and the oxidation state becomes higher. The unit cell parameters also change, parameter a becomes larger, while the c becomes smaller. At the same time, the high discharge current density has a catalytic effect on the structural transformation, and in terms of high charging voltage, the surface structure changes to a rock salt phase. The cathode material is covered by a 3-nm-thick and discontinuous rock salt phase after cycling 50 times at the current density of 100 mA g〈sup〉−1〈/sup〉. However, when the material is cycled at the current density of 1000 mA g〈sup〉−1〈/sup〉, the rock salt phase becomes thicker (5∼7-nm-thick) and more continuous, which leads to a fast capacity fading.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Julieta S. Riva, Andrea V. Juárez, Silvia E. Urreta, Lidia M. Yudi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fe〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Pd binary alloy nanowires (NWs) were synthesized by electrodeposition method with the assistance of nanoporous anodic alumina (AAO). We focus on the synthesis conditions of Fe〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Pd nanowires and the characterization of the resulting composition, size and morphology, and their magnetic and catalytic properties at liquid/liquid interfaces. A number of factors may affect the formation and properties of nanoparticles during the synthesis. Here, we focused on finding the effect of the applied potential on the resulting NWs. Moreover, it is shown that Fe〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Pd NWs catalyse ion transfer across a soft water/1,2-dichloroethane interface, with a lower overpotential to that reported at bare soft interfaces. Furthermore, the NWs' motion at a liquid/liquid interface is monitored by optical microscopy which allows demonstrating that the magnetic field generated by the ionic current makes the NWs to act as nano-stirrers, improving the local flow of material towards the active sites of the catalyst. During cyclic voltammetry experiments magnetic nanowires move back and forth in a given direction at the liquid/liquid interface according to the direction of polarization.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618327671-fx1.jpg" width="484" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Yihui Li, Kun Chang, Hongwei Tang, Bao Li, Yalei Qin, Yan Hou, Zhaorong Chang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To address the large structural and volume changes of commercial WO〈sub〉3〈/sub〉 during charge/discharge, which make this material unsuitable for use in Li-ion batteries (LIBs), we herein prepared oxygen deficient WO〈sub〉3-〈em〉x〈/em〉〈/sub〉 nanosheets on a large scale by thermal treatment of ammonium paratungstate in a reducing atmosphere followed by sonication and freeze-drying. The above nanosheets were employed as LIB anode materials and exhibited a specific capacity and cycling stability significantly exceeding those of oxygen-deficient WO〈sub〉3-〈em〉x〈/em〉〈/sub〉 nanoparticles and commercial WO〈sub〉3〈/sub〉. In addition, we investigated the effect of nanosheet loading on electrode performance, demonstrating that the best results (Li storage capacity of ∼628 mAh g〈sup〉−1〈/sup〉 after 100 cycles at 100 mA g〈sup〉−1〈/sup〉) were obtained at a nanosheet content of 20 wt%. This excellent performance was ascribe to the good exposure of defects caused by the comparatively small size of WO〈sub〉3-〈em〉x〈/em〉〈/sub〉 nanosheets, which resulted in an increased number of sites and diffusion paths available for Li-ion storage and transfer. The novel electrode-optimized strategy may be extended to the fabrication of other electrodes that use nanomaterials as active substances due to its superior comprehensive performance and low cost.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618328561-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Le Li, De-Kun Ma, Feixuanyu Qi, Wei Chen, Shaoming Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nanostructured Bi electrocatalysts for CO〈sub〉2〈/sub〉 reduction have attracted much attention because of their many advantages such as low cost, good stability, environmentally friendly nature, and ease of synthesis. However, it is critical to further enhance its electrocatalytic performance from the perspective of practical application. Considering that grain boundaries (GBs) possess highly active sites and can tune the selectivity of the products through stabilizing the reaction intermediates, here Bi nanoparticles/Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanosheets (Bi NPs/Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 NSs) with abundant GBs were synthesized through a controlled hydrothermal reduction route. The as-obtained products showed a considerable partial current density (24.4 mA cm〈sup〉−2〈/sup〉), high selectivity (∼100%), and excellent durability (〉24 h) for the electrocatalytic CO〈sub〉2〈/sub〉 reduction into formate. Our work showed that microstructures of Bi derived from chemical reduction rather than conventional electrochemical reduction played key roles in the aspect of boosting their electrocatalytic CO〈sub〉2〈/sub〉 reduction performance. GBs engineering provided a new strategy for designing highly efficient CO〈sub〉2〈/sub〉 reduction electrocatalysts.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618328263-fx1.jpg" width="464" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Nabi Ullah, Wentong Zhao, Xiaoqing Lu, Chidinma Judith Oluigbo, Sayyar Ali Shah, Mingmei Zhang, Jimin Xie, Yuanguo Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, an efficient and cheap electrocatalysts are prepared by a simple synthetic method for oxygen evolution reaction (OER) hydrogen evolution reaction (HER). Nickel/nickel oxide@3dimensional hierarchical porous graphene (Ni-NiO@3DHPG) and cobalt/cobalt oxide@3dimensional hierarchical porous graphene (Co-CoO@3DHPG) electrocatalysts were obtained from cation exchange resin, nickel acetate and cobalt nitrate as a source of carbon, Ni and Co respectively. In Ni-NiO@3DHPG and Co-CoO@3DHPG, metal and metal oxide nanoparticles embedded in the graphene layers, were confirmed by different techniques. The 3-D graphene in Ni-NiO@3DHPG and Co-CoO@3DHPG were thinned wall and highly porous structure and large specific surface area. The Ni-NiO@3DHPG composite displays onset potential, overpotential (10 mA cm〈sup〉−2〈/sup〉) and Tafel value of are 1.53 V, 1.64 V and 55 mV dec〈sup〉−1〈/sup〉 for OER and −0.18 V, −0.31 V and 78 mV dec〈sup〉−1〈/sup〉 for HER respectively. Similarly, Co-CoO@3DHPG catalyst show onset potential, overpotential (10 mA cm〈sup〉−2〈/sup〉) and Tafel are 1.59 V, 1.68 V and 65 mV dec〈sup〉−1〈/sup〉 for OER and −0.26 V, −0.40 V and 85 mV dec〈sup〉−1〈/sup〉 for HER respectively. Electrocatalysts show good stability after 4 h continuously. This simple synthetic method will open a new way for cheap and efficient electrocatalysts of other types of non-precious metals for OER and HER.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉A simple method was used to in situ grown Ni-NiO and Co-CoO in three dimensional hierarchical porous graphene by ion exchange/activation method. The obtained Ni-NiO@3DHPG and Co-CoO@3DHPG show efficient performance for OER and HER. the better performance of Ni-NiO@3DHPG and Co-CoO@3DHPG are due to well dispersion of Ni-NiO and Co-CoO particle in graphene layers and high conductivity of graphene layer which facilitate fast transport of electron.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618327518-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 298〈/p〉 〈p〉Author(s): Gillian Priske, ZhangFei Su, Fatemeh Abbasi, Jacek Lipkowski, France-Isabelle Auzanneau〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Two 4-thio pseudo-glycolipids, a disulfide and a thiol, were synthesized as candidates to build tethered bilayer lipid membranes (tBLMs) on gold (111) surface. Monolayers of the disulfide and thiol were built on gold surfaces using the self-assembly and Langmuir-Blodgett (LB) transfer methods. Monolayers were prepared in several solvents and at various temperatures; their quality was assessed by differential capacitance. Best monolayers were achieved when the disulfide was self-assembled in ethanol. The quality of such monolayers was further improved by allowing the assembly to proceed under stirring of the solution at increased temperatures. The charge number per adsorbed molecule and surface concentration of disulfide on gold (111) surface were determined by chronocoulometry. A DPhPC/disulfide tBLM was then built by vesicle fusion of 1,2-diphytanyl-〈em〉sn〈/em〉-glycero-3-phosphocholine (DPhPC) on top of the disulfide monolayer. The minimum capacitance of the gold electrode with tBLM (1.3 μF cm〈sup〉−2〈/sup〉) was close to the value of a real cell membrane and the AFM force spectroscopy measurements showed that the DPhPC/disulfide tBLM had a thickness of 6.2 ± 0.6 nm consistent with the thickness expected for a bilayer. Finally, the potential of the tBLM to study transmembrane proteins was assessed by investigating the reconstitution of gramicidin A into the membrane by polarization modulation infrared absorption spectroscopy (PM-IRRAS). These results demonstrate that the disulfide is a good candidate to construct tBLMs on gold surface and to study transmembrane proteins.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468618327464-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉