ALBERT

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 319〈/p〉 〈p〉Author(s): Subish John, Samba Siva Vadla, Somnath C. Roy〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉CuO is a narrow band gap 〈em〉p〈/em〉-type semiconducting material having a wide range of applications. However, it is quite challenging to obtain phase pure CuO nanostructures grown directly on Cu substrate as most of the synthesis techniques like thermal oxidation results in the formation of additional Cu〈sub〉2〈/sub〉O phase. In this work, we report the growth of CuO nanoflakes without the formation of Cu〈sub〉2〈/sub〉O by a facile two-step synthesis process which consist of electrochemical anodization of Cu foil followed by low-temperature hydrothermal treatment at 100 °C. The phase purity of the sample is confirmed through XRD, XPS, and HRTEM. Further, photocurrent response of the sample is evaluated, and a rapid thermal treatment was used to improve the photo-response without altering the phase and morphology of the CuO nanoflakes. Such a process at 400 °C for 10 s resulted in a high photocurrent density of −4.6 mAcm〈sup〉−2〈/sup〉 (at 0.05 V 〈em〉vs.〈/em〉 RHE under AM 1.5G conditions). Electrochemical impedance spectroscopy and Mott Schottky analysis shows the direct role of rapid thermal treatment in increasing the charge carrier density of the sample.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619313337-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 319〈/p〉 〈p〉Author(s): Cong Liu, Fenyun Yi, Dong Shu, Weixin Chen, Xiaoping Zhou, Zhenhua Zhu, Ronghua Zeng, Aimei Gao, Chun He, Xia Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Three-dimensional N/S co-doped succulent-like hierarchical carbon (3D NS-SHC) is synthesized by carbonization of a supramolecular cluster. In this supramolecular process, potassium citrate can act as a reliable carbon source, while the thiourea as a N/S source and then, two molecules gradually tend to generate a giant “all-in-one” precursor via hydrogen bonding verified by Independent Gradient Model (IGM) calculation. TEM and SEM images show the N/S co-doped carbon holds a novel 3D succulent-like hierarchical structure. For NS-SHC-8:8 sample, element mapping images display the uniform N/S atoms distribution. These distinct features can be related to the supramolecular polymerization which promotes in-situ N/S co-doping homogenously and conduces to build 3D structure. Typically, NS-SHC-8:8 electrode exhibits prominent specific capacitance (258.5 F g〈sup〉−1〈/sup〉 at 0.5 A g〈sup〉−1〈/sup〉) and excellent cycle stability (94.4% after 20000 cycles) in three-electrode system. Furthermore, an assembled quasi-solid state symmetric supercapacitor delivers good energy density (10.2 Wh kg〈sup〉−1〈/sup〉 at 250 W kg〈sup〉−1〈/sup〉) and steady cycle endurance (85.1% after 10000 cycles). These eximious behaviors of NS-SHC-8:8 are mainly attributed to (1) the uniform N/S atoms distribution and their synergistic effect, which brings extra Faradaic reaction to higher specific capacitance, (2) the charming 3D succulent-like hierarchical structure, which serves as a multifunctional reservoir that can accommodate the ion/charge and facilitate their migration to further promote the electrochemical performance. Above mentions suggest that this uniformly heteroatom-modified carbon material produced by supramolecular technique is promising for high-performance 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-S0013468619313283-fx1.jpg" width="296" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 319〈/p〉 〈p〉Author(s): Arunprabaharan Subramanian, Mahadeo A. Mahadik, Jin-Woo Park, In Kwon Jeong, Hee-Suk Chung, Hyun Hwi Lee, Sun Hee Choi, Weon-Sik Chae, Jum Suk Jang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Herein, we report the surface treatment on Zr〈sup〉4+〈/sup〉/Al〈sup〉3+〈/sup〉 codoped α-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 photoanode for high-performance photoelectrochemical water splitting. A high-temperature quenching exhibits the Zr〈sup〉4+〈/sup〉/Al〈sup〉3+〈/sup〉 codoping in α-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 photoanode without damaging morphology. The presence of Zr〈sup〉4+〈/sup〉/Al〈sup〉3+〈/sup〉 codoping shows a cathodic shift in onset potential, but lack of increment in photocurrent reveals the major role of passivation and the minimum doping effect of aluminum. Additionally, CoO〈sub〉x〈/sub〉 cocatalyst exhibits increment in photocurrent with the greater cathodic shift in onset potential than the pristine α-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanorods. The CoO〈sub〉x〈/sub〉 surface-reworked Zr〈sup〉4+〈/sup〉/Al〈sup〉3+〈/sup〉 codoped α-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 photoanode displays the highest photocurrent of 1.5 mA/cm〈sup〉2〈/sup〉 at 1.23 V vs. RHE (76% increment over the pristine α-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉) and 0.7 mA/cm〈sup〉2〈/sup〉 at 1.0 V vs. RHE (102% increment over the pristine α-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉). The systematic characterization carried out using x-ray diffraction and scanning electron microscopy confirms that after Zr〈sup〉4+〈/sup〉/Al〈sup〉3+〈/sup〉 codoping, and surface treatment, the crystalline structure, and morphology of the photoanodes remains unchanged. X-ray photoelectron spectroscopy confirmed the existence of Zr〈sup〉4+〈/sup〉/Al〈sup〉3+〈/sup〉 codopants in the hematite nanostructure. The electrochemical properties of the photoanode suggest that Al〈sup〉3+〈/sup〉 and Zr〈sup〉4+〈/sup〉 codoping, as well as surface treatment with CoO〈sub〉x〈/sub〉, cocatalyst lowers charge transfer resistance across the FTO/hematite interface, and hematite/electrolyte interface. This designs not only lowers onset potential but also offers the blueprint for the development of an efficient catalyst for solar water oxidation.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉CoO〈sub〉x〈/sub〉 surface-reworked Zr〈sup〉4+〈/sup〉/Al〈sup〉3+〈/sup〉 codoped α-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 photoanode displays the 102% increment in PEC performance than pristine α-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 at 1.0 V vs. RHE.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619312927-fx1.jpg" width="471" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 319〈/p〉 〈p〉Author(s): Jeonghoon Han, Changwoo Bae, Songhwa Chae, Dukhyun Choi, Sangmin Lee, Youngsuk Nam, Choongyeop Lee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Here we introduce the new approach to high-efficiency power generation from a salinity difference using conventional nanoporous Nafion membrane. When access areas on each side of nanoporous Nafion membrane are set to be asymmetric, the ratio of ionic current upon a voltage bias of the different polarity also becomes asymmetric, resulting in ionic diode phenomena. When this geometrical ionic diode effect is combined with a salinity gradient, it can help significantly improve the energy conversion efficiency from a salinity difference even under a hyper-saline environment with a large salinity difference, e.g. ∼41% conversion efficiency and ∼120 nW power generation with 1 M KCl and 1000-fold salinity difference, both of which are comparable with the best performances reported in the previous studies. We propose that the decrease in ion concentration polarization at a low salt concentration side is responsible for the enhanced power generation with the membrane having asymmetric access areas. Our approach is simple to implement and can be applicable to any nanoporous membrane to enhance the power generation from a salinity difference.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 319〈/p〉 〈p〉Author(s): Jialun Chen, Ping Tong, Lingting Huang, Zhonghua Yu, Dianping Tang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An interdigitated capacitance immunosensing system based enzymatic biocatalytic precipitation on micro-comb electrode was designed for the sensitive detection of prostate-specific antigen (PSA) by coupling Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉 MXenes with tyramine signal amplification strategy. The immunosensor was prepared by immobilizing anti-PSA capture antibody on MXenes-coated interdigitated electrode, whereas gold nanoparticles heavily functionalized with horseradish peroxidase (HRP) and detection antibody were utilized as the signal-transducer tags. Introduction of interdigitated electrode was expected to enhance the sensitivity of capacitance immunosensor. This system mainly consisted of the sandwich-type immunoreaction, formation of tyramine-HRP repeats on gold nanoparticle and enzymatic biocatalytic precipitation. The concatenated HRP through the tyramine oxidized numerous 4-chloro-1-naphthol molecules into insoluble benzo-4-chlorohexadienone with the help of H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉, and coated the modified immunosensor to keep free ions away from the electrode, thus causing the local alteration in the capacitance. Under optimum conditions, the change of the immunosensor in the capacitance increased with the increasing target PSA concentrations from 0.1 ng mL〈sup〉−1〈/sup〉 to 50 ng mL〈sup〉−1〈/sup〉 at a detection limit of 0.031 ng mL〈sup〉−1〈/sup〉. Moreover, the interdigitated capacitance immunosensor showed good reproducibility, high specificity and acceptable accuracy for the analysis of human serum specimens in comparison with those obtained from commercial human PSA ELISA kit. Importantly, Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉 MXenes-based interdigitated capacitance transducer open new opportunities for protein diagnostics and biosecurity.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 319〈/p〉 〈p〉Author(s): Zhixu Jian, Honglei Li, Rui Cao, Heliang Zhou, Huaizhe Xu, Guangjin Zhao, Yalan Xing, Shichao Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Confining the dissolution and diffusion of polysulfide is considered a key factor in the realization of high-performance lithium-sulfur battery. Here, we report a polydopamine (pDA) coated sulfur-carbon composite with a unique hierarchical tower-like structure (S-HTC@pDA) for lithium sulfur cathode. The internal layer by layer structure is capable of uniformly dispersing of sulfur, providing a continuous electronic conductive path and shortening the Li〈sup〉+〈/sup〉 transport distance, while the external pDA coating can inhibit the diffusion of polysulfide. Benefited from the smart design, the S-HTC@pDA electrode achieved an excellent cycling stability, realizing a high discharge capacity of 916 mAh g〈sup〉−1〈/sup〉 at the first cycle and a capacity retention of 79.4% after 500 cycles at 1 C. Therefore, this work provides a new concept in structure design for high performance lithium sulfur cathodes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Here, we report a polydopamine (pDA) coated sulfur-carbon composite with a unique hierarchical tower-like structure (S-HTC@pDA) for lithium sulfur cathode. The internal layer by layer structure is capable of uniformly dispersing of sulfur, providing a continuous electronic conductive path and shortening the Li〈sup〉+〈/sup〉 transport distance, while the external pDA coating can inhibit the diffusion of polysulfide.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619312885-fx1.jpg" width="326" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 319〈/p〉 〈p〉Author(s): Xiao-Hu Dai, Hao-Xiang Fan, Jia-Jia Zhang, Shi-Jie Yuan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pyrolysis gradually becomes a promising green method to dispose the sewage sludge who has brought serious problems to environment. In this study, hierarchical porous hollow carbon nanospheres are directly obtained by specific carbonization/activation procedures using sewage sludge as the only precursor for the first time. The resultant carbon possesses tailor-made hierarchically porous structure with larger surface area (1518.40 m〈sup〉2〈/sup〉 g〈sup〉−1〈/sup〉), high pore volume (1.21 cm〈sup〉3〈/sup〉 g〈sup〉−1〈/sup〉), and rich oxygenic functional groups, which is favorable for lithium ion diffusion and can better enhance the ionic conductivity in an electrode system. As anode for li-ion battery, the carbon displays superior discharge capacity, which reaches 1168.9 mAh g〈sup〉−1〈/sup〉 at 0.1 A g〈sup〉−1〈/sup〉 and 287.1 mAh g〈sup〉−1〈/sup〉 at 2 A g〈sup〉−1〈/sup〉. And the capacitance retention is 98.7% over 100 cycles at 0.1 A g〈sup〉−1〈/sup〉. Therefore, it is anticipated that such a pollutants-derived carbon can facilitate the development of new green and sustainable pathways for the construction and design of well-defined porous carbon nanospheres to ease energy and environmental issues.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619313313-fx1.jpg" width="245" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 319〈/p〉 〈p〉Author(s): Diego Di Girolamo, Marco Piccinni, Fabio Matteocci, Andrea Giacomo Marrani, Robertino Zanoni, Danilo Dini〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electrodeposition of NiOOH is an attracting route toward nanosized films of NiO, a p-type semiconductor used in many advanced applications. In this paper, the deposition mechanism is thoroughly investigated aiming at the clarification of the deposition dynamics and the chemical nature of the deposit. We focused on initial stages of the potentiostatic deposition on ITO, which yields a nanostructured film. In the potential range investigated the process is mass transport controlled and strongly overlaps with oxygen evolution reaction. The nucleation regime, which is finely tunable, correlates with the surface extension of the film. Supporting electrolytes are found to suppress the deposition, likely by modifying the nickel speciation in the aqueous electrolyte. Further, through XPS investigation we shed light on the mixed 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mi〉γ〈/mi〉〈mo linebreak="goodbreak" linebreakstyle="after"〉−〈/mo〉〈mi〉β〈/mi〉〈/mrow〉〈/math〉 NiOOH nature of the deposited film and its electrochemistry. This work provides precious understanding for future exploitations of anodic electrodeposited NiO, especially in applications where a strict control on surface morphology and thickness at the nanoscale level is mandatory.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 319〈/p〉 〈p〉Author(s): Leszek Zaraska, Karolina Gawlak, Ewelina Wiercigroch, Kamilla Malek, Marcin Kozieł, Mariusz Andrzejczuk, Mateusz M. Marzec, Magdalena Jarosz, Agnieszka Brzózka, Grzegorz D. Sulka〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, the effect of the thermal annealing on the composition of crack-free anodic tin oxide layers with different channel diameters, formed in 1 M NaOH at 2 and 4 V, was investigated in detail. STEM tomography confirmed that anodic oxides formed at 2 V have narrower channels, higher porosity, and higher surface area than those anodized at 4 V. Structural properties of oxides films were studied using different techniques such as X-ray diffraction, Raman spectroscopy, and UV-Vis diffuse reflectance spectroscopy. In addition, Raman imaging was employed to study local changes in the composition of anodic films. The photoelectrochemical performance of as-formed and annealed oxides was correlated with applied anodizing potential and annealing conditions. It was found that as-formed anodic oxides are composed of poorly crystalline SnO〈sub〉2-x〈/sub〉 with a significant amount of Sn〈sup〉2+〈/sup〉 defects. When the oxide layers were annealed at 200 °C, crystallization of the SnO phase was observed, however, the amount of Sn〈sup〉2+〈/sup〉 defects was not drastically reduced. A significant reduction of Sn〈sup〉2+〈/sup〉 defects occurred at 400 °C due to a formation of intermediate Sn〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 oxide and, in the final result, more stoichiometric and crystalline SnO〈sub〉2〈/sub〉 was formed. We proved that appropriate design of anodizing and annealing procedures can lead to the formation of nanoporous tin oxide layers with controlled morphology, composition and, in consequence, photoelectrochemical properties.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 318〈/p〉 〈p〉Author(s): Álvaro Torrinha, Maria C.B.S.M. Montenegro, Alberto N. Araújo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study the development of a biofuel cell for potential application in microfluidics is described. The biocatalysts support is produced through vacuum-filtration of a Vulcan carbon black suspension resulting in flexible, paper-like electrodes. The glucose oxidase bioanode was assembled using an enzyme precipitate coating procedure whereas the biocathode was implemented by attaching bilirubin oxidase enzyme onto the carbon black surface via a pyrene intermediate. The bioelectrodes were first characterized by voltammetry and by chronoamperometry on their sensing ability towards the respective substrates, namely glucose and oxygen. Finally, bioanode and biocathode were integrated in a single-compartment of a heterogeneous poly (methyl methacrylate) - polydimethylsiloxane microfluidic platform and the power density produced was assessed. In 10 mM glucose solution at pH 7.0, the biofuel cell showed an open circuit potential (OCP) of 0.43 V and a maximum power density of about 28 μW cm〈sup〉−2〈/sup〉 at 0.24 V. Also we demonstrate here the viability of human propelled fluidics by introducing in the microfluidic device a finger-pressure mechanism.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 318〈/p〉 〈p〉Author(s): Ling Huang, Hao Wu, Heng Liu, Yun Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Earth-abundant water splitting electrocatalysts with high activity and robust stability are in great demand for realizing efficient sustainable energy conversion and storage. Here, we propose a multi-elements composition-engineering approach to construct phosphorous (P) doped cobalt iron sulfide (CoFeS) hybrids for efficient water electrocatalysis. Through the combination of Co and P co-doping, nanostructuring, and hybridization with carbon nanotubes (CNTs), we demonstrate that the designed CoFeSP/CNT with optimum composition is superior bifunctional electrocatalyst for both hydrogen and oxygen evolution reaction (HER and OER). When employed as a hydrogen-evolution electrode, the as-synthesized CoFeSP/CNT are found to be stable and active in both acid and alkaline electrolytes. When used as an oxygen-evolution electrode, the in-situ electrochemical generated CoFe-oxyhydroxides exhibits excellent performance where low overpotentials of 262 and 309 mV achieved at a current density of 10 and 100 mA cm〈sup〉−2〈/sup〉, respectively. Moreover, a two-electrode alkaline water electrolyzer constructed with three dimensional CoFeSP nanorods on carbon cloth (CoFeSP/CC) can afford a current density of 50 mA cm〈sup〉−2〈/sup〉 at a voltage of 1.62 V.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉A composition-tailoring strategy with cation and anion co-doping has been developed for the synthesis of P doped CoFeS nanoparticles anchored on carbon nanotubes, the catalyst surface is highly P-rich, which manifest superior electrocatalytic performance in both hydrogen evolution reaction and oxygen evolution reaction.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619312393-fx1.jpg" width="315" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 318〈/p〉 〈p〉Author(s): João P.F. Grilo, Daniel A. Macedo, Rubens M. Nascimento, Fernando M.B. Marques〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Samples of Gd-doped ceria (GDC, Ce〈sub〉0.9〈/sub〉Gd〈sub〉0.1〈/sub〉O〈sub〉1.95〈/sub〉) with eutectic mixtures of Na〈sub〉2〈/sub〉CO〈sub〉3〈/sub〉 and Li〈sub〉2〈/sub〉CO〈sub〉3〈/sub〉 (NLC), or K〈sub〉2〈/sub〉CO〈sub〉3〈/sub〉, Na〈sub〉2〈/sub〉CO〈sub〉3〈/sub〉 and Li〈sub〉2〈/sub〉CO〈sub〉3〈/sub〉 (KNLC) as sintering aids (5 mol%) were studied against pure GDC and cobalt doped GDC. The former electrolytes reached densifications in excess of 95% when sintered at 1100 °C, values comparable to pure GDC sintered at 1500 °C, and more than 20% higher than for GDC sintered at 1100 °C. X-ray diffraction powder patterns showed only typical GDC peaks without any noticeable lattice modification and microstructural analysis suggested a homogeneous distribution of residual amounts of sintering aids. The electrical properties of all materials were studied by impedance spectroscopy in air from 200 to 750 °C. Materials with NLC and KNLC showed a total ionic conductivity matching pure GDC at 600 °C. Hebb-Wagner polarization measurements, used to assess the impact of sintering aids on the n and p-type electronic conductivity of GDC (600–750 °C) showed that NLC and KNLC additions lower the p-type conductivity of GDC while Co additions have the opposite effect. The efficacy of alkali metal salts to produce ceria-based electrolytes with competitive ionic and electronic transport properties is exposed.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉K, Na and Li carbonates sintering aids lower σ〈sub〉p〈/sub〉 with respect to GDC or Co-doped GDC.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619312915-fx1.jpg" width="280" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 318〈/p〉 〈p〉Author(s): Xiangjian Liu, Lin Zhou, Liang Huang, Lulu Chen, Ling Long, Siyu Wang, Xiaolong Xu, Minchao Liu, Wenxiu Yang, Jianbo Jia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Transition metal phosphides have attracted much research interests in energy conversion and storage as a result of their enhanced physiochemical properties. Here, we report the successful synthesis of tri-metal (CoNiFe) based porous hierarchical hollow sphere-like phosphides through a simple solvothermal process and a low temperature phosphorization process. The special nanostructure endows the phosphide electrocatalyst a rough surface, which in turn provides much more active sites and defects to enhance the performances in oxygen evolution reaction (OER) and lithium storage. The synergetic effects among the metal elements and combination with the advantages of metal phosphides contribute mostly to the enhanced performances. The optimized electrocatalyst exhibits a low overpotential of 279 mV at 10 mA cm〈sup〉−2〈/sup〉 and a Tafel slope of 62.9 mV dec〈sup〉−1〈/sup〉 for OER. Benefiting from the structural and compositional advantages of the phosphide catalyst, it also shows good stability and high capacity in lithium storage.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉ZIF-67 derived hollow sphere-like CoNiFe phosphides are synthesized with enhanced performance on oxygen evolution reaction (OER) and lithium storage property.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619312794-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 318〈/p〉 〈p〉Author(s): Xuedong Wei, Na Li, Nan Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Usually, metallic organic frameworks (MOFs) based electrocatalysts are prepared by pyrolysis of MOFs. And it is improved that the research on direct use of MOFs as electrocatalysts through the development of two-dimensional (2D) shaped MOFs direction is feasible. In this paper, a kind of ultrathin NiFeZn-MOF nanosheets containing few metal oxide nanoparticles grown on nickel foam (NiFeZn-MNS/NF) are successfully synthesized, and they are used as catalyst for the oxygen evolution reaction (OER) and overall water splitting. The NiFeZn-MNS/NF catalyst behaves the most excellent electrocatalytic performance with the best overpotential of 350 mV at 50 mA cm〈sup〉−2〈/sup〉 and has the best current density stability with the 5% drop of the initial polarization current density at the end of 120 h. The voltage of NiFeZn-MNS/NF as a bifunctional overall water-splitting catalyst is 1.52 V at the current density of 10 mA cm〈sup〉−2〈/sup〉, which is superior to commercial noble metal electrocatalytic combination of RuO〈sub〉2〈/sub〉/NF(+)//Pt-C/NF(−)(1.63 V). The structure and morphology of the nanosheets and the synergistic effect of nickel, iron and zinc ions enhance the catalytic activity. While the addition of zinc ion promotes the rapid growth of nanosheets on nickel foams, which further improves the stability of nanosheets.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 318〈/p〉 〈p〉Author(s): Ying Wang, Lan Huang, Lunhong Ai, Mei Wang, Zehui Fan, Jing Jiang, Hongqi Sun, Shaobin Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The electronic properties of semiconducting electrocatalysts are of fundamental research interest and of great importance for oxygen evolution reaction (OER) from water splitting. Engineering the band levels is a promising route to design and fabricate nonprecious earth-abundant semiconducting electrocatalysts for OER. Herein, p-type semiconductor electrocatalysts of ultrathin nickel-cobalt inorganic-organic hydroxide hybrid nanobelts [Co〈sub〉x〈/sub〉Ni〈sub〉1-x〈/sub〉(OH)(BzO)·H〈sub〉2〈/sub〉O, 〈em〉x〈/em〉 = 0, 0.2, 0.5, 0.8, 1.0, BzO: benzoate] with favorable band structures are proposed. The Co〈sub〉x〈/sub〉Ni〈sub〉1-x〈/sub〉(OH)(BzO)·H〈sub〉2〈/sub〉O with the energetically favorable flat band level and well matched p-p junction exhibit remarkable OER performances in alkaline environment. The optimal Co〈sub〉0.8〈/sub〉Ni〈sub〉0.2〈/sub〉(OH)(BzO)·H〈sub〉2〈/sub〉O nanobelt electrocatalyst with nearly 4 nm in thickness achieves the superior OER performance, showing earlier onset potential (E〈sub〉onset〈/sub〉: 1.50 V vs RHE), smaller overpotential (η〈sub〉10〈/sub〉: 319 mV) as well as significantly enhanced stability compared with those of IrO〈sub〉2〈/sub〉 reference (E〈sub〉onset〈/sub〉: 1.51 V vs RHE and η〈sub〉10〈/sub〉: 343 mV) and most previously reported OER electrocatalysts. This electronic engineering strategy would provide a new insight to the fundamental understanding of underlying OER mechanism as well as open a new avenue to rational design of semiconducting electrocatalysts with high performances.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S001346861931223X-fx1.jpg" width="257" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 318〈/p〉 〈p〉Author(s): Chuanyu Sun, Keti Vezzù, Gioele Pagot, Angeloclaudio Nale, Yannick Herve Bang, Giuseppe Pace, Enrico Negro, Chiara Gambaro, Laura Meda, Thomas A. Zawodzinski, Vito Di Noto〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of samples are collected from the catholyte solution of a vanadium redox flow battery (VRFB) at different values of state of charge (SoC)/state of discharge (SoD). The samples are analyzed by means of Raman spectroscopy to identify: (i) the species present into the catholyte; and (ii) how the composition of the catholyte is modulated along the charge and discharge processes of the VRFB. Raman results reveal that the most abundant species in the catholye are VO〈sup〉2+〈/sup〉 and VO〈sub〉2〈/sub〉〈sup〉+〈/sup〉; they are coordinated by HSO〈sub〉4〈/sub〉〈sup〉−〈/sup〉 and SO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉 ligands. During the charge process of the VRFB the equilibrium between the vanadium species is shifted towards the formation of an ensemble of V(V) complexes. Instead, during discharge a family of V(IV) species is obtained. The formation of concatenated HV〈sub〉2〈/sub〉O〈sub〉5〈/sub〉〈sup〉−〈/sup〉 and H〈sub〉3〈/sub〉V〈sub〉2〈/sub〉O〈sub〉7〈/sub〉〈sup〉−〈/sup〉 species in the catholyte is revealed, which indicates that side electrochemical reactions occur during the charge and discharge processes of a VRFB. The presence of these side reactions plays a crucial role in the modulation of the Coulombic efficiency of the VRFB. This work highlights the complexity of the chemical situation at a VRFB cathode, and the great importance to understand/control such chemical situation to improve the performance of VRFBs in the scenario of electrochemical energy storage field.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 318〈/p〉 〈p〉Author(s): Kartick Chandra Majhi, Paramita Karfa, Rashmi Madhuri〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The development of highly active, durable, and inexpensive bifunctional catalysts towards both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is one of the most challenging tasks in the term of renewable energy. Keeping in mind the current scenario, herein, we have synthesized bimetallic transition metal chalcogenides (CoTe〈sub〉2〈/sub〉@CdTe and CoSe〈sub〉2〈/sub〉@CdSe) by a very easy, single step hydrothermal process. During the synthesis, two different morphologies (i.e. spherical and wire) were obtained depending on the selection of chalcogen. It was found that Te based nanocomposite i.e. CoTe〈sub〉2〈/sub〉@CdTe showed a symmetrical nanowire array morphology with a high electrocatalytic surface area and good electrocatalytic activity towards both HER and OER. The structural, morphological and electrochemical features of synthesized nanocomposites were characterized by various useful techniques (like field emission scanning electron microscopy, high resolution transmission electron microscopy, powder X-ray diffraction analysis etc.) to confirm their successful synthesis. The CoTe〈sub〉2〈/sub〉@CdTe nanowire array has shown a small onset potential value, high current density, low Tafel slope value along with high stability towards overall water splitting.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 318〈/p〉 〈p〉Author(s): Xusheng Wang, Chang Li, Chunyi Liu, Luxiang Ma, Rui Li, Jitao Chen, Mianqi Xue〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Main attention to the interlayer regulation of layered metal chalcogenides (LMCs) is focused on the expansion of interlayer spacing to improve the Li〈sup〉+〈/sup〉-storage performance. However, the issues of poor material homogeneity and complicated preparation make this strategy incapable to realize a wider application. In this work, a new interlayer design of the oriented growth of layered (00〈em〉l〈/em〉) facets enables facile Li〈sup〉+〈/sup〉-diffusion channels in SnSSe nanosheets. The further assembly between SnSSe nanosheets and reduced graphene oxide (SnSSe/rGO) generates flexible freestanding electrodes, in which the SnSSe nanosheets are tiled onto the rGO nanolayers with a planar configuration. The SnSSe/rGO electrodes demonstrate an ultrahigh discharge capacity of 2049 mAh g〈sup〉−1〈/sup〉 at 0.1 A g〈sup〉−1〈/sup〉 (based on the active mass of SnSSe) and a considerable capacity retention of 82% after 2000 cycles at 1 A g〈sup〉−1〈/sup〉. The morphological characterization of long-life cycled SnSSe/rGO electrode confirms an open structure built with vertical lamellas, which can provide more active sites and accommodate the volume expansion–contraction of SnSSe nanosheets.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619311855-fx1.jpg" width="284" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 318〈/p〉 〈p〉Author(s): Wei Zou, Fan-Jie Xia, Jian-Ping Song, Liang Wu, Liang-Dan Chen, Hao Chen, Yang Liu, Wen-Da Dong, Si-Jia Wu, Zhi-Yi Hu, Jing Liu, Hong-En Wang, Li-Hua Chen, Yu Li, Dong-Liang Peng, Bao-Lian Su〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The voltage fade of Li-rich layered oxide cathode material Li〈sub〉1.2〈/sub〉Ni〈sub〉0.13〈/sub〉Co〈sub〉0.13〈/sub〉Mn〈sub〉0.54〈/sub〉O〈sub〉2〈/sub〉 (LNCM) heavily hinders its application in Li-ion batteries. Herein, we revisit the origin of the voltage fade of LNCM and propose a solution to suppress this effect. It is demonstrated that the voltage fade of the LNCM cathode comes from the structural change of the crystal from layer structure to spinel structure, involving all the cations rearrangement. Such rearrangement of all the cations in LNCM is due to the high degree of delithiation and oxygen release at high cutoff voltage of 4.8 V. It is also evidenced that nickel and cobalt change from low valence to high valence at the discharged state, which not only inhibits the transport of lithium ions, but also leads to the loss of high voltage platforms. In particular, the cation rearrangement of Li/Mn causes valence change from Mn〈sup〉4+〈/sup〉 to Mn〈sup〉3+〈/sup〉, resulting in the decrease of discharge voltage platform at the cutoff voltage of 4.8 V much higher than at 4.6 V. The lower charge cutoff voltage can be a solution to suppress the voltage fade of LNCM cathode materials and have a good stability of LNCM cathode materials without compromising the battery performance.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619312629-fx1.jpg" width="237" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 318〈/p〉 〈p〉Author(s): Norbert Weber, Steffen Landgraf, Kashif Mushtaq, Michael Nimtz, Paolo Personnettaz, Tom Weier, Ji Zhao, Donald Sadoway〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The electrical potential in a battery jumps at each electrode-electrolyte interface. We present a model for computing three-dimensional current and potential distributions, which accounts for such internal voltage jumps. Within the framework of the finite volume method we discretize the Laplace and gradient operators such that they account for internal jump boundary conditions. After implementing a simple battery model in OpenFOAM we validate it using an analytical test case, and show its capabilities by simulating the current distribution and discharge curve of a Li‖Bi liquid metal battery.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 322〈/p〉 〈p〉Author(s): M. Safrany Renard, R. Baddour-Hadjean, J.P. Pereira-Ramos〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The kinetics of the electrochemical Na reaction in the γ′-V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 polymorph prepared by the carboreduction route is investigated by electrochemical impedance spectroscopy. This cathode material with puckered layer structure is capable of delivering a high discharge capacity of 143 mAh g〈sup〉−1〈/sup〉 at a relatively high operating voltage of 3.3 V vs. Na〈sup〉+〈/sup〉/Na. In spite of a good cyclability, a low efficiency of the first charge process limits yet the value of the stable capacity of this material upon cycling. The present study intends to give further insight into the sodium insertion-extraction mechanism in γ′-V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 by achieving a picture of the main kinetic parameters as a function of Na uptake in γ-Na〈sub〉x〈/sub〉V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 electrodes (0 ≤ x ≤ 0.97). We show that the evolution of cathode impedance, charge transfer resistance, double layer capacity and apparent chemical Na diffusion coefficient are highly correlated to the structural changes induced upon sodiation. A faster Na diffusion is revealed in the richest 0.6 〈 x ≤ 0.97 solid solution region while electron transport is slowed down in that composition domain due to the highly localized electron character of the sodiated phase. A significant modification of the surface area is also underlined, undoubtedly caused by the high volume expansion experienced during sodiation. The low efficiency of the first cycle, characterized by an important polarization at the end of the charge, is explained by a huge increase in the electrode impedance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 28 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta〈/p〉 〈p〉Author(s): Weiheng Li, Qiu-An Huang, Changping Yang, Jian Chen, Zhepeng Tang, Fangzhou Zhang, Aijun Li, Lei Zhang, Jiujun Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fast impedance measurement via complex Morlet wavelet transform (CMWT) offers a valuable way for real-time diagnosis and in-situ monitoring on electrochemical energy devices. However, it normally suffers from a dilemma: how to set CMWT parameters such as sampling duration 〈em〉T〈/em〉〈sub〉〈em〉p〈/em〉〈/sub〉, sampling frequency 〈em〉f〈/em〉〈sub〉〈em〉s〈/em〉〈/sub〉, scale factor range 〈em〉A〈/em〉, central frequency 〈em〉f〈/em〉〈sub〉〈em〉c〈/em〉〈/sub〉, and band factor 〈em〉f〈/em〉〈sub〉〈em〉b〈/em〉〈/sub〉? Especially for a fast measurement of Warburg-like impedance spectra. Thus, optimal theories are needed in order to acquire Warburg-like impedance spectra rapidly under a required precision and a given frequency range. In this paper, the optimal rules for a fast impedance measurement are developed based on the uncertainty principle: 1) 2.5/f〈sub〉L〈/sub〉 ≤ 〈em〉T〈/em〉〈sub〉〈em〉p〈/em〉〈/sub〉 ≤ 3.0/f〈sub〉L〈/sub〉; 2) 〈em〉f〈/em〉〈sub〉〈em〉s〈/em〉〈/sub〉〈em〉 ≥ 〈/em〉20f〈sub〉U〈/sub〉; 3) 1.0/〈em〉f〈/em〉〈sub〉〈em〉c〈/em〉〈/sub〉≤〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈msqrt〉〈mrow〉〈msub〉〈mrow〉〈mi〉f〈/mi〉〈/mrow〉〈mrow〉〈mi〉b〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/msqrt〉〈/mrow〉〈/math〉≤1.4/〈em〉f〈/em〉〈sub〉〈em〉c〈/em〉〈/sub〉 where f〈sub〉L〈/sub〉 and f〈sub〉U〈/sub〉 are the lower-limit and upper-limit frequencies of the impedance spectra, respectively. Subsequently, measurement errors are quantitatively evaluated for the reconstructed impedance spectra via CMWT algorithm. Through the derived optimal rules, a fast measurement with 〈em〉T〈/em〉〈sub〉〈em〉p〈/em〉〈/sub〉〈em〉 = 〈/em〉28.0 s and 〈em〉f〈/em〉〈sub〉〈em〉s〈/em〉〈/sub〉〈em〉 = 〈/em〉20.0 kHz is implemented for Warburg-like impedance spectra from 0.1 Hz to 1.0 kHz and with the average errors of 0.7% and 2.6% for magnitude and phase, respectively. The developed method creates a higher possibility for real-time diagnosis and in-situ monitoring of electrochemical energy devices in electric vehicles (EVs).〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619316317-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 322〈/p〉 〈p〉Author(s): Jingping Zhong, Lili Li, Muhammad Waqas, Xiaoqu Wang, Youjun Fan, Jiuhui Qi, Bo Yang, Chuyan Rong, Wei Chen, Shigang Sun〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Deep eutectic solvents are promising in the green synthesis of advanced functional materials owing to their several distinct advantages including good solubility, wide electrochemical window, high conductivity, low cost, nontoxicity and tolerance to humidity. Herein, we report a novel green protocol to design the hybrid PtCu nanoclusters on multi-walled carbon nanotubes in deep eutectic solvents medium without adding any surface controlling agent. Subsequently, the structure, elemental composition and electrocatalytic aspects of the as-synthesized nanohybrids are characterized by transmission electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopic features and electrochemical investigations. Typically, the synthesis medium plays a key role to control the dispersion of Pt-based nanoparticles and to enhance the electronic transfer interaction among the catalytic nanoparticles and support material. On other hand, the addition of alloyed Cu not only further decreases the crystallite size of catalytic particles but also results in the formation of cluster nanostructure with the coarse surface. Moreover, the methanol oxidation electrocatalytic activity of the as-fabricated material is clearly composition dependent, their maximum mass activity (Pt/Cu mass ratio 1:0.25) is about 2.5 times that of the carbon nanotubes-supported monometallic Pt catalyst. And it also presents the good CO-tolerance ability and evident long-term electrochemical durability. This study suggests that the synthesis strategy in deep eutectic solvents is of great importance to design and fabricate the high-performance electrocatalysts for fuel cells applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta〈/p〉 〈p〉Author(s): Rajendran Ramachandran, Changhui Zhao, Muniyandi Rajkumar, Krishnamoorthy Rajavel, Pengli Zhu, Wenlu Xuan, Zong-Xiang Xu, Fei Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The porous structure of three-dimensional NiO microspheres on titanium carbide (NiO/Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉T〈sub〉x〈/sub〉) is prepared by calcination of Ni-MOF/Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉T〈sub〉x〈/sub〉 in the air. The crystalline structure and morphology of the obtained hybrid are characterized with various tools such as X-ray photoelectron spectroscopy and X-ray diffraction, scanning electron microscope, transmission electron microscope, and Brunauer-Emmett-Teller surface analyzer techniques. As-prepared NiO/Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉T〈sub〉x〈/sub〉 hybrid is used for two noteworthy applications in electrochemistry like supercapacitor and non-enzymatic hydrogen peroxide (H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉) sensor. NiO/Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉T〈sub〉x〈/sub〉 electrode exhibited an enhanced specific capacity of 630.9 C g〈sup〉−1〈/sup〉 at a current density of 1 A g〈sup〉−1〈/sup〉 in comparison to pure NiO (376.8 C g〈sup〉−1〈/sup〉). Furthermore, the H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 sensing performance of the NiO/Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉T〈sub〉x〈/sub〉 modified glassy carbon electrode is evaluated in 0.5 M of NaOH solution and the electrode showed a low detection limit of 0.34 μM with a wider range of linear response 10 μM to 4.5 mM. The higher specific surface area and porosity of NiO/Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉T〈sub〉x〈/sub〉 allow more electro-active site for electrochemical redox reactions in the direction of H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 sensing and supercapacitor. Moreover, Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉T〈sub〉x〈/sub〉 prevents from fouling in 3D porous network and leaching effect, and beneficial for easy access of electrolyte ions and efficient electron transport to the electrode surface resulted in improved electrochemical applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Bin Liu, Hongming Zhou, Chengjie Yin, Hao Guan, Jian Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Spinel LiNi〈sub〉0.5〈/sub〉Mn〈sub〉1.5〈/sub〉O〈sub〉4〈/sub〉(LNMO) cathode with high voltage plateau at around 4.7 V (vs. Li/Li〈sup〉+〈/sup〉) and high energy density has attracted great attention. However, its application is limited because of the lack of matched electrolyte. Herein, we demonstrate that lithium difluorophosphate (LiPO〈sub〉2〈/sub〉F〈sub〉2〈/sub〉, LiDFP) as lithium difluoro(oxalate)borate (LiODFB) electrolyte additive significantly improves the electrochemical performance of high voltage LNMO/Li half cells and LNMO/G full cells at room temperature. Capacity retention of LNMO/Li half cell with 4% LiDFP achieves 89.69% after 200 cycles in comparison with 76.31% of that without LiDFP. Even discharging at 10C, the LNMO/Li half cell with 4% LiDFP still delivers a discharge capacity of 76.25 mAh g〈sup〉−1〈/sup〉 and maintains at 75.94% capacity retention after 200 cycles. The electrochemical performance of LNMO/G full cells has a similar improvement. The enhanced electrochemical performance of LNMO can be ascribed to the steady and low-impedance cathode electrolyte interphase (CEI) film formed by priority decomposition of LiDFP. Besides, in order to further reveal the mechanism of film-forming additive, we studied on the changes of CEI film during initial cycles using transmission electron microscopies (TEM), X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectrometer (FT-IR) and electrochemical impedance spectroscopy (EIS) measurements. The results indicate that the LiDFP preferential decomposition product can gradually prevent the contact between the electrolyte and the cathode with the growth of the CEI film, thereby reducing decomposition of the electrolyte. The finally grown CEI film is sufficiently dense to effectively isolate the electrolyte and the cathode, and CEI film formed by LiDFP-containing electrolyte is more conducive to the transmission of Li〈sup〉+〈/sup〉,eventually leading to excellent electrochemical performance for the high-voltage LIBs.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 322〈/p〉 〈p〉Author(s): Ivan S. Filimonenkov, Sergey Ya Istomin, Evgeny V. Antipov, Galina A. Tsirlina, Elena R. Savinova〈/p〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta〈/p〉 〈p〉Author(s): Mingqing Hua, Fen Cui, Yunpeng Huang, Yan Zhao, Jiabiao Lian, Jian Bao, Bo Zhang, Shouqi Yuan, Huaming Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Engineering nanostructured architecture with a hierarchically arranged active surface is regarded as an effective strategy to develop advanced electrode materials. Herein, nanosheet-built MnCo〈sub〉2〈/sub〉S〈sub〉4〈/sub〉 micro-disks with abundant nano-pores are synthesized and uniformly dispersed on a three-dimensional nitrogen-doped carbon matrix (3DNC). In the resultant 3DNC@MnCo〈sub〉2〈/sub〉S〈sub〉4〈/sub〉 composite architecture, N-doped carbon network provides interconnected and shortened pathways for fast ion transmission and charge transfer, and the nanosheet-built MnCo〈sub〉2〈/sub〉S〈sub〉4〈/sub〉 disks allow the efficient Faradaic redox process through the increased active surface. Due to the compositional and structural advantages, prepared 3DNC@MnCo〈sub〉2〈/sub〉S〈sub〉4〈/sub〉 composite architecture delivers a superior electrochemical capacitive performance than 3DNC@MnCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 and other sulphospinel-based electrodes (including a high specific capacitance of 1812 F g〈sup〉−1〈/sup〉 at 1A g〈sup〉−1〈/sup〉, and a high rate performance of 82.9% capacitance retention at 20 A g〈sup〉−1〈/sup〉). When assembled into hybrid supercapacitor device, the 3DNC@MnCo〈sub〉2〈/sub〉S〈sub〉4〈/sub〉//AC HSC also exhibits a high energy density of 68.8 Wh kg〈sup〉−1〈/sup〉 at the power density of 800 W kg〈sup〉−1〈/sup〉 and excellent cycling stability (82% capacitance retention after 5000 cycles at the current density of 10 A g〈sup〉−1〈/sup〉). The facile yet efficient construction of this 3D porous electrode provides an innovative method for developing high-performance energy storage devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Jaione Martínez De Ilarduya, Laida Otaegui, Montserrat Galcerán, Laura Acebo, Devaraj Shanmukaraj, Teófilo Rojo, Michel Armand〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The sodium deficiency issue of Na〈sub〉0.67〈/sub〉[Fe〈sub〉0.5〈/sub〉Mn〈sub〉0.5〈/sub〉]O〈sub〉2〈/sub〉, P2-type layered oxide, is compensated with the addition of Na〈sub〉2〈/sub〉C〈sub〉4〈/sub〉O〈sub〉4〈/sub〉 as sacrificial salt. Na〈sub〉2〈/sub〉C〈sub〉4〈/sub〉O〈sub〉4〈/sub〉 is easy to synthesize and stable, which makes it easy to handle and scale-up. Sodium-free hard carbon anode and sodium-deficient layered oxide cathode, mixed with different amounts of Na〈sub〉2〈/sub〉C〈sub〉4〈/sub〉O〈sub〉4〈/sub〉, are used to assemble Na-ion full-cells and evaluate the effect of the sacrificial salt content in the electrochemical performance of the cells. 〈em〉Ex-situ〈/em〉 SEM and XRD analyses confirmed that the Na〈sup〉+〈/sup〉 ions formed as a result of the electrochemical decomposition of the salt, are reinserted back into the cathode structure. Thus, Na〈sub〉0.67〈/sub〉[Fe〈sub〉0.5〈/sub〉Mn〈sub〉0.5〈/sub〉]O〈sub〉2〈/sub〉 undergoes same phase transitions when tested as full-cell using Na-free hard carbon or with a Naº anode that compensates for the Na deficiency. In comparison with NaN〈sub〉3〈/sub〉 sacrificial salt, Na〈sub〉2〈/sub〉C〈sub〉4〈/sub〉O〈sub〉4〈/sub〉 seems to be a better candidate as sodiation agent in terms of safety and handling. The electrochemical performance of the P2-type layered oxide with 31% of Na〈sub〉2〈/sub〉C〈sub〉4〈/sub〉O〈sub〉4〈/sub〉 sacrificial salt outperforms the cathode with NaN〈sub〉3〈/sub〉 with improved cycling stability, delivering a reversible capacity of 155 mAh g〈sup〉−1〈/sup〉 and an energy density of 165 Wh kg〈sup〉−1〈/sup〉.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta〈/p〉 〈p〉Author(s): Min Chen, Can Wang, Yingcai Wang, Xiaoyang Meng, Zefang Chen, Weiqiu Zhang, George Tan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, a novel Ti-enhanced nanotube arrays/SnO〈sub〉2〈/sub〉-Sb electrode was prepared by the sol-gel method on enhanced TiO〈sub〉2〈/sub〉 nanotube arrays (ENTA). The characterization, degradation performance, oxidation mechanism and mass transfer impact of the novel electrode was investigated. Compared with the conventional Ti/SnO〈sub〉2〈/sub〉-Sb electrode, our novel electrode has higher oxygen evolution potential and electrochemical stability, due to the fabrication of ENTA structure. Its application for the destruction of a common biocide of MIT (2-methyl-4-isothiazolin-3-one), the first-order rate constants were determined from 0.01 min〈sup〉−1〈/sup〉 to 0.505 min〈sup〉−1〈/sup〉 during the electrochemical process. The radical oxidation and non-radical oxidation of the MIT degradation contribution were quantitatively identified as 87.8% and 12.1%, respectively. Furthermore, the second-rate constant between hydroxyl radical and MIT was estimated at 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mn〉3.72〈/mn〉〈mo linebreak="goodbreak" linebreakstyle="after"〉×〈/mo〉〈msup〉〈mrow〉〈mn〉10〈/mn〉〈/mrow〉〈mrow〉〈mn〉9〈/mn〉〈/mrow〉〈/msup〉〈msup〉〈mrow〉〈mi〉M〈/mi〉〈/mrow〉〈mrow〉〈mo〉−〈/mo〉〈mn〉1〈/mn〉〈/mrow〉〈/msup〉〈msup〉〈mrow〉〈mi〉S〈/mi〉〈/mrow〉〈mrow〉〈mo〉−〈/mo〉〈mn〉1〈/mn〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉. The mass transfer impact was investigated with a differential column batch reactor (DCBR) under the conditions of various electrode spacing and fluid velocities. It indicated that reducing the electrode spacing and increasing the fluid velocity would enhance the mass transfer process and increase the overall oxidation rate. Meanwhile, the EE/O decreased from 17.7 kWh m〈sup〉−3〈/sup〉 to 9.7 kWh m〈sup〉−3〈/sup〉, and the mass transfer coefficients increased dramatically from 0.52 × 10〈sup〉−6〈/sup〉 m s〈sup〉−1〈/sup〉 to 2.48 × 10〈sup〉−6〈/sup〉 m 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-S0013468619316500-fx1.jpg" width="408" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta〈/p〉 〈p〉Author(s): Kamal Kanti Bera, Malay Chakraborty, Sreya Roy Chowdhury, Apurba Ray, Sachindranath Das, Swapan Kumar Bhattacharya〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pt-nanoparticle decorated nano-sized ZnO–Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 hetero-junctions of various compositions are synthesized along with binary Pt–ZnO and Pt–Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, characterized and used as anode-catalysts for methanol oxidation reaction in alkali. The peak current density of most of the Pt–ZnO–Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 catalysts in cyclic voltammetry is higher than these of Pt– Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and Pt– ZnO indicating beneficiary and synergistic effect of the ternary composites. The best Pt–ZnO–Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 electrode containing ZnO:Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 = 5:1, exhibits significantly high current density, 932.1 mA mg〈sup〉−1〈/sup〉 Pt which is 9.7, 5.5 and 12.1 times higher than that of Pt–Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 (95.4), Pt–ZnO (167.8) and synthesized Pt (76.5) catalysts. The mass normalized equilibrium exchange current density (4.46 × 10〈sup〉−4〈/sup〉 mA mg〈sup〉−1〈/sup〉 Pt) towards methanol oxidation reaction on the best electrode is approximately 3.6 × 10〈sup〉4〈/sup〉 and 9.5 times higher than these on Pt–Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and Pt–ZnO electrodes. The chronoamperometry conforms to the results of CV study. The charge transfer resistance of the catalyst obtained from Nyquist plot is 12.6 and 8.2 times less than these offered by Pt–Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and Pt–ZnO catalysts. Multi-scan CV experiments with the best ternary composite shows excellent stability in catalytic activity towards methanol oxidation reaction. The HPLC study helps understanding the selectivity of the catalysts among various products, which facilitates prediction of mechanistic pathways.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619316469-fx1.jpg" width="266" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta〈/p〉 〈p〉Author(s): Thomas Holm, Svein Sunde, Frode Seland, David A. Harrington〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Data from a combined cyclic voltammetry and dynamic electrochemical impedance spectroscopy (dEIS) study of the methanol oxidation reaction (MOR) at high temperatures was revisited using a new method for mechanistic modeling. Through iterative optimization of kinetic parameters, a total of five reaction mechanisms of the indirect pathway of the MOR were modeled. The calculated dEIS spectra from the kinetic parameters were used to verify the reaction mechanisms and best fits were found where i) water adsorption is reversible and hinders the MOR at lower potentials (¡ 0.50 V vs RHE), and ii) the surface reaction between adsorbed CO and OH is chemical.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619316354-fx1.jpg" width="298" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Haritha Hareendrakrishnakumar, Reshma Chulliyote, Mary Gladis Joseph, Shruti Suriyakumar, Arul Manuel Stephan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lithium-sulfur (Li–S) batteries possess great attention for energy storage owing to its high theoretical capacity and energy density compared to the state-of-the-art lithium-ion technology. However, the commercialization of Li–S battery is still at bottleneck due to the several technical problems, of which polysulfide shuttle effect is the major challenge. To minimize the shuttling of polysulfides by confining them within the cathode compartment, a novel lithium ion conducting organic polymer lithium poly(2-acrylamido-2-methyl-1-propanesulfonate) (LPAMPS) coated Celgard separator (LPAMPS@CG) was designed by simple doctor blade coating technique. The negatively charged –SO〈sub〉3〈/sub〉̄ groups present in LPAMPS coating works as an electrostatic shield for soluble polysulfide anions through coulombic repulsion without inhibiting the transport of Li〈sup〉+〈/sup〉. The Li–S cell containing LPAMPS@CG not only reduces shuttling effect but also enhances the electrolyte wettability, interfacial property and ionic conductivity. The cell with LPAMPS@CG separator delivered an initial discharge capacity of 1486 mAh g〈sup〉−1〈/sup〉 at 0.1C, and a discharge capacity of 1061 mAh g〈sup〉−1〈/sup〉 was retained after 200 cycles. Furthermore, the cells containing LPAMPS@CG exhibited excellent rate capability and anti-self-discharge rate.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Sulfonic (–SO〈sub〉3〈/sub〉̄) groups containing functional separator impart an “electrostatic repulsion” to mitigate polysulfide shuttle effect in Li–S battery.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619315683-fx1.jpg" width="435" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Nannan Lu, Bo Zheng, Yue Gu, Xiaoyi Yan, Tingting Zhang, He Liu, Haixin Xu, Zhiqian Xu, Xuwen Li, Zhiquan Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Rational construction of biosensor to determine reactive oxygen species (ROS) generated from living cells is one of the great challenges in physiological and pathological fields. Herein, for the first time, a novel Co nanoparticles (CoNPs) embedded walnut-like N-doped porous carbon microsphere (Co@NCS) can be synthesized using dual imprinting strategy by pyrolysis and acid leaching. The distinct morphology and chemical characteristic of melamine cyanurate (MC) aggregates can be imprinted in the carbon source derived from glucose during the pyrolysis process. According to our research, with synergistic effect of CoNPs and NCS, the Co@NCS shows an excellent electrochemical activity toward the reduction of hydrogen peroxide (H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉). The Co@NCS modified electrode exhibits a wider linear detection response with the range from 0.5 μM to 7500 μM and a low detection limit of 88 nM (S/N = 3). Moreover, with desirable selectivity, decent reproducibility and satisfied anti-interference performance, the fabricated biosensor can be applied to determine H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 in human serum samples and that released from living cell, indicating the potential applications in the fields of pathological and physiological sensing.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Francisco José García-García, Jadra Mosa, Agustín R. González-Elipe, Mario Aparicio〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉WO〈sub〉3〈/sub〉 thin film electrodes were successfully prepared by magnetron sputtering (MS) deposition under an oblique angle configuration (OAD). Intercalation of Na ions in the tungsten oxide layers has been studied using electrochemical techniques. Sample characterization before and after sodium intercalation has been carried out by Raman, XPS and XRD measurements. ToF-SIMS analysis has been also performed in order to analyze the element depth profiles along the electrode thickness. Electron microscopy evaluation of the cross section confirms the porous structure of the coatings. Batteries integrating these WO〈sub〉3〈/sub〉 electrodes have a discharge capacity of 120 mA h g〈sup〉−1〈/sup〉 at the initial cycles and show an adequate capacity retention upon 300 cycles. The WO〈sub〉3〈/sub〉-OAD thin-films are proposed as promising electrodes for Na-ion batteries.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Ranxi Liang, Anjun Hu, Minglu Li, Zhiqun Ran, Chaozhu Shu, Jianping Long〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Interface engineering is crucial strategy for the sensible design and synthesis of high-efficiency electrocatalysts. However, the study on the effect of interfacial heterogeneity on the kinetics of oxygen electrode reactions in lithium-oxygen (Li-O〈sub〉2〈/sub〉) batteries tends to be neglected, which restricts the development of excellent performance Li-O〈sub〉2〈/sub〉 batteries. Here, a cactus-like nickel-cobalt oxide and nickel oxide heterostructure (NCO@NO) was successfully prepared and used for Li-O〈sub〉2〈/sub〉 batteries as catalyst. The built-in electric field at the heterogeneous interface between NiO and NiCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 can significantly enhance the interface charge transfer kinetics, and its unique cactus-like structure facilitates the exposure of abundant catalytic active sites. Due to the synergistic interaction between surface structure and heterogeneous interface, the NCO@NO based cathode exhibits a large discharge capacity of 17463.5 mA h g〈sup〉−1〈/sup〉, an improved overpotential of 0.98 V, and an excellent long-term cycle stability (the terminal discharge voltage of the NCO@NO based Li-O〈sub〉2〈/sub〉 battery shows negligible attenuation after cycling up to 500 times).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Weihao Yin, Wenwen Chai, Ke Wang, Wenkai Ye, Yichuan Rui, Bohejin Tang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel multi-step method that combines solvothermal, sulfidation and polymerization process was utilized to synthesize Antimony Sulfide/Meso@Microporous Carbon nanofibers@polypyrrole (Sb〈sub〉2〈/sub〉S〈sub〉3〈/sub〉/MMCN@ppy) composite. As the host, the MMCN is full of microporous and mesoporous naturally, which can prevent the aggregation during the sulfidation process and accelerate the transfer of electron inside the whole composite. Meanwhile, the effective coverage of ppy layer can accommodate the volume changes during cycling and fast the electron transfer on the surface of the composite. Combining those merits, the dual physical barrier composed of MMCN and conductive ppy layer guarantees the ultrastable structure for superior electrochemical performance. When used as an anode for lithium-ion batteries, Sb〈sub〉2〈/sub〉S〈sub〉3〈/sub〉/MMCN@ppy composite demonstrates the stable electrochemical performance with an enhanced lithium-storage capability. Impressively, even at the high current density of 1000 mA g〈sup〉−1〈/sup〉, a specific reversible capacity about 556 mA h g〈sup〉−1〈/sup〉 can be delivered after 300 long cycles. In addition, Sb〈sub〉2〈/sub〉S〈sub〉3〈/sub〉/MMCN@ppy composite also displays the outstanding stability sodium-storage property in sodium-ion batteries (269 mAh g〈sup〉−1〈/sup〉 at 1000 mA g〈sup〉−1〈/sup〉 after 300 long cycles). The results show that this product may be considered as a promising anode material for advanced LIBs and SIBs.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): D.-W. Choi, M. Ohashi, C.A. Lozano, J.W. Vanzee, P. Aungkavattana, S. Shimpalee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The contamination effect of hydrogen sulfide on micro-tubular solid oxide fuel cells was investigated using various electrochemical techniques. The cells, mechanically supported by cupper tube, were provided by National Metal and Materials Technology Center, and they contain the electrode materials of nickel and yttria stabilized zirconia cermet for anode and lanthanum strontium manganate for cathode. Pure hydrogen and hydrogen gas containing diluted hydrogen sulfide were repeatedly switched for the anode feed at the constant cell voltage of 0.9 V. Exposure times of 30 and 60 min were applied to study the effects of the poisoning interval. Then, the obtained results were analyzed. Herein, we reported two effects that had not been reported previously: the poisoning interval effect on the same hydrogen sulfide dosage and the poisoning sulfur-transport effect to the cathode surface. In the same dosage experiment, the recovery process was required before complete adsorption of sulfur species, and it supported not to fully block active sites of hydrogen adsorption and oxidation, and thus it would expand a cell lifespan on the contamination. In the analysis, different contamination steps between short and long term exposure time were presented, and thermodynamic parameters were calculated. Also, transport of elemental sulfur from the anode to the cathode surface was presented using the energy dispersive X-ray spectroscopy technique. The results appear to be strong evidence for the transport of sulfur from anode to cathode, and this means that the effect of sulfur diffusion to the cathode should be considered one major reason for performance degradation. This paper provides additional possible reasons regarding the performance degradation on hydrogen sulfide contamination, and serves as a guide to overcome the barrier of the sulfur contamination.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Lulu Chai, Linjie Zhang, Xian Wang, Zuju Ma, Ting-Ting Li, Huan Li, Yue Hu, Jinjie Qian, Shaoming Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the field of renewable energy, the core of advanced materials lies in the efficiency for the electrocatalytic and photoelectrochemical overall water splitting. However, in hydrogen evolution reaction (HER), there is a lack of electrocatalysts based transition metals of high-performance and natural-abundance, and thus there is a formidable challenge for large-scale application. Therefore, molybdenum carbide (Mo〈sub〉2〈/sub〉C) based catalysts and their composites are regarded as a most promising and replacement noble metal electrocatalyst for the HER in different media about all pH. In this work, the preparation of ultra-fine Mo〈sub〉2〈/sub〉C nanoparticles, which uniformly implant into hollow N-doped carbon polyhedrons (Mo〈sub〉2〈/sub〉C@HNCPs) by adopting MOF-assisted self-sacrifice template approach, is proposed. Mo〈sub〉2〈/sub〉C@HNCPs showcases suitable catalytic activity and feasible stability toward HER in both media such as acidic and alkaline solutions. The as-prepared Mo〈sub〉2〈/sub〉C@HNCPs exhibits effective and fast response from the HER region with nearly 0.0 V onset overpotentials, only requiring 89 mV (0.5 M H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 media) and 87 mV (1.0 M KOH media) overpotential to reach 10 mA cm〈sup〉−2〈/sup〉 and cycling stability (〈5% performance loss after 10 h). Such distinctive activity of HER is mainly imputed to the poly-dispersion of the ultra-fine Mo〈sub〉2〈/sub〉C nanoparticles and its synergistic contribution of rich nitrogen doping, unique hollow morphology, and abundant active sites at the heterostructures.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉The synthesis of ultra-fine Mo〈sub〉2〈/sub〉C nanoparticles is uniformly embedded into hollow N-doped carbon polyhedrons (Mo〈sub〉2〈/sub〉C@HNCPs) by a MOF-assisted self-sacrifice template approach. As the HER electrocatalyst, Mo〈sub〉2〈/sub〉C@HNCPs shows better catalytic activity and feasible stability toward HER in both acidic and alkaline media. Such HER activity is attributed to the ultra-fine Mo〈sub〉2〈/sub〉C nanoparticles and synergistic contribution of nitrogen doping, unique hollow structure, and abundant active sites at the heterostructures.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619315518-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Bhusankar Talluri, Sourav Ghosh, G. Ranga Rao, Tiju Thomas〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ultra-small (r 〈 2 nm), semiconductor quantum dots (QDs) based composites are underexplored in electrochemical energy-storage devices. This is due to practical challenges associated with synthesis of QDs such as (i) stabilization, (ii) scalability, and (iii) achieving monodispersed population. In this context, ultra-small, highly monodispersed copper oxide QDs (∼2.5 ± 0.4 nm) have been synthesized by using soft-chemical and scalable approach based on digestive ripening. Composites of digestively ripened (〈em〉DRd〈/em〉) copper oxide QDs deposited on graphene oxide are tested electrochemically for battery-like supercapacitor. The composites are grown in-situ on a Ni-foam to make binder-free battery-like supercapacitor electrode by hydrothermal process. Results indicates that battery-like behavior of the composites. Among the composites, 50%QDs-GO provides maximum specific capacity of 191 mA h g〈sup〉−1〈/sup〉 at 2 mV s〈sup〉−1〈/sup〉 which is maintained up to 63 mA h g〈sup〉−1〈/sup〉 even at a high scan rate of 200 mV s〈sup〉−1〈/sup〉. The specific capacity increases ∼4 times for the 50%QDs-GO composite, compared to the graphene oxide. The maximum energy density provided by the system is 57.2 Wh kg〈sup〉−1〈/sup〉 at 2 mV s〈sup〉−1〈/sup〉. Specific capacity and charge-discharge stability of the composites are found to be improved with increasing concentration of QDs. This is the first report on deployment of 〈em〉DRd〈/em〉 copper oxide QDs in battery-like supercapacitors and it opens up possibilities for further exploration of other 〈em〉DRd〈/em〉 QDs.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619315804-fx1.jpg" width="251" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Qiwen Zhang, Yongli Shen, Yufan Hou, Liting Yang, Baili Chen, Zhen Lei, Weiqing Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The composition-activity relationship is highly desirable for electrocatalytic nitrogen reduction reaction (NRR) because it could guide the rational design of efficient NRR catalysts. In this work, the composition effect of Ag-based alloy nanotubes on electrocatalytic NRR activity is systematically investigated. It is found that, among AgAu nanotubes with atomic ratio from 8:1 to 1:2, Ag〈sub〉2〈/sub〉Au〈sub〉1〈/sub〉 alloy nanotubes achieve the largest enhancement for NRR catalytic activity. Specifically, the NH〈sub〉3〈/sub〉 production rate and faradaic efficiency of Ag〈sub〉2〈/sub〉Au〈sub〉1〈/sub〉 nanotubes are 21.7 μg h〈sup〉−1〈/sup〉 mg〈sub〉cat〈/sub〉〈sup〉−1〈/sup〉 and 3.8% at −0.30 V vs. RHE, respectively, which were 3.0 and 3.6 times higher than those of Ag nanowires. Compared with Ag〈sub〉2〈/sub〉Pd〈sub〉1〈/sub〉 and Ag〈sub〉2〈/sub〉Pt〈sub〉1〈/sub〉 nanotubes, Ag〈sub〉2〈/sub〉Au〈sub〉1〈/sub〉 hollow nanotubes also exhibit a better NRR catalytic activity. Theoretical calculation results indicate that the negative ion characteristic of Au atoms in the Ag〈sub〉2〈/sub〉Au〈sub〉1〈/sub〉 alloy is favorable for the adsorption and activation of N〈sub〉2〈/sub〉. Moreover, Ag〈sub〉2〈/sub〉Au〈sub〉1〈/sub〉 nanotubes showed stable NH〈sub〉3〈/sub〉 yield rate and faradaic efficiency up to 18 h, revealing its great potential for promising NRR electrocatalysis.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619315622-fx1.jpg" width="341" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Obaidallah Munteshari, Yucheng Zhou, Bing-Ang Mei, Laurent Pilon〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study theoretically and rigorously validates the use of the recently proposed step potential electrochemical spectroscopy (SPECS) and multiple potential step chronoamperometry (MUSCA) methods and their fitting analysis for determining the respective contributions of electrical double layer (EDL) and faradaic reactions to charge storage in pseudocapacitive electrodes. The continuum modified Poisson-Nernst-Planck model coupled with the Frumkin-Butler-Volmer theory were used for simulating interfacial, transport, and electrochemical phenomena in pseudocapacitive electrodes. The model accounted for (i) electron transport in the electrode, (ii) reversible redox reactions, (iii) ion electrodiffusion in binary and symmetric electrolytes, (iv) ion intercalation into the pseudocapacitive electrode, and (v) steric repulsion due to finite ion size. First, typical experimental measurements obtained from the SPECS method were reproduced numerically for a planar pseudocapacitive electrode. The EDL and faradaic currents retrieved from the SPECS fitting procedure were found to be in excellent agreement with those defined from first principles and computed numerically. Here, the faradaic current was modeled in the SPECS method as a diffusion process accounting for interfacial charge transfer kinetics and IR drop. The resistance obtained by SPECS matched the internal resistance obtained from electrochemical impedance spectroscopy. Similarly, the EDL capacitance retrieved by SPECS corresponded to the differential capacitance obtained from cyclic voltammetry (CV). Finally, the CV curves were successfully corrected for ohmic polarization effect using the MUSCA method. Then, the capacitive and diffusive currents retrieved from the electrochemical analysis of CV curves corrected by the MUSCA method were in good agreement with the EDL and faradaic currents reconstructed from the MUSCA method.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619315075-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): A. Endrikat, N. Borisenko, A. Ispas, R. Peipmann, F. Endres, A. Bund〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The electrochemical reduction mechanism of niobium was studied in the ionic liquid 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate ([BMP][OTf]) containing niobium halides (NbCl〈sub〉5〈/sub〉 and NbF〈sub〉5〈/sub〉). The influence of the electrolyte composition, temperature, and nature of the substrate were systematically investigated. 〈em〉In situ〈/em〉 electrochemical techniques, such as cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical quartz crystal microbalance (EQCM) and rotating ring disc electrode (RRDE), were used, besides the 〈em〉ex situ〈/em〉 characterization techniques scanning electron microscopy (SEM) and vibrational spectroscopy. The number of transferred electrons was estimated from the half width of the cathodic peaks in the DPV measurements. Furthermore, the product of the diffusion coefficient and the number of transferred electrons at the power of 3/2 were evaluated from RRDE measurements to be approx. 3 × 10〈sup〉−10〈/sup〉 m〈sup〉2〈/sup〉/s. Thicker and better adherent niobium-based deposits were obtained from NbCl〈sub〉5〈/sub〉 in [BMP][OTf] than from NbF〈sub〉5〈/sub〉 in [BMP][OTf]. EQCM measurements combined with DPV indicated the potential region where niobium-based deposits could be obtained as well as their stoichiometry.〈/p〉 〈p〉Vibrational spectroscopy reveals that NbF〈sub〉5〈/sub〉 and NbCl〈sub〉5〈/sub〉 interact differently with [BMP][OTf]. The spectra show that in the case of NbF〈sub〉5〈/sub〉 – [BMP][OTf] only niobium(V) anionic species [NbF〈sub〉6〈/sub〉A]〈sup〉2-〈/sup〉 and [NbF〈sub〉5〈/sub〉A]〈sup〉-〈/sup〉 (where A = [OTf]〈sup〉-〈/sup〉) are formed, while in NbCl〈sub〉5〈/sub〉 – [BMP][OTf] both niobium(V) and niobium(IV) anionic species are present. At low NbCl〈sub〉5〈/sub〉 concentrations, [NbCl〈sub〉4〈/sub〉A〈sub〉2〈/sub〉]〈sup〉2-〈/sup〉 and [NbCl〈sub〉4〈/sub〉A〈sub〉2〈/sub〉]〈sup〉-〈/sup〉 are obtained, while at high NbCl〈sub〉5〈/sub〉 concentration, [NbCl〈sub〉5〈/sub〉A]〈sup〉2-〈/sup〉 and [NbCl〈sub〉5〈/sub〉A]〈sup〉-〈/sup〉 are found. The electrochemical niobium reduction mechanism depends on temperature and on the anionic species that are involved in the reduction process. In the case of NbCl〈sub〉5〈/sub〉 – [BMP][OTf], at high cathodic potentials the formation of subvalent Nb-clusters (possibly Nb〈sub〉6〈/sub〉Cl〈sub〉14〈/sub〉) was observed.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Rui Wang, Kaiwen Lin, Fengxing Jiang, Weiqiang Zhou, Zhenfeng Wang, Yanli Wu, Yongbo Ding, Jian Hou, Guangming Nie, Jingkun Xu, Xuemin Duan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fluoropolymers have great values in the scientific research and the industrial application, but poor electrochemical properties restricted their use as charge storage materials. In this work, we developed a high-performance poly(5-fluoroindole) (5-PFIn) as charge storage material by simple electrodeposition of 5-fluoroindole in acetonitrile solution containing 0.1 M Bu〈sub〉4〈/sub〉NBF〈sub〉4〈/sub〉. The morphologies, structures and electrochemical properties of as-prepared 5-PFIn were studied by SEM, FT-IR, UV–vis, BET and electrochemical techniques, respectively. The electrochemical results indicated that the 5-PFIn nanowires in 1.0 M H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 electrolyte showed a full-covered strongly responsive redox behavior between −0.4 V and 0.85 V, which remarkably differed from polyindole (PIn) and poly(5-methoxyindole) (5-PMeOIn) and poly(indole-5-carboxylic acid) (5-PICA). As a result, 5-PFIn exhibited high specific capacitance of 416 F g〈sup〉−1〈/sup〉 at 10 A g〈sup〉−1〈/sup〉, good cycling stability of 83% after 5000 cycles and slow self-discharge behavior, which were superior to those of PIn (103 F g〈sup〉−1〈/sup〉, 68%), 5-PMeOIn (114 F g〈sup〉−1〈/sup〉, 70%) and 5-PICA (286 F g〈sup〉−1〈/sup〉, 70%). These results indicated that the fluorine-substituted conjugated PIn will be one of the most promising fluoropolymers electrode materials for supercapacitor application.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Xueying Li, Xiu Qian, Yalin Xu, Hui Wu, Yuanyuan Dan, Lizhuang Chen, Qing Yu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The key issue of developing the metal phosphides based electrode material is to explore the green synthesis approach and maintain the structural stability during practical applications. Herein, we report a facile electrodeposition approach combined with subsequent thermal treatment to grow Fe–Co–P on the porous carbon membrane with Magnolia leaves as precursor (Fe–Co–P/C). The three-dimensional porous carbon frameworks as substrate provide superior electrical conductivity for Fe–Co–P/C electrodes. The strong coupling between Fe–Co–P and porous carbon framework keeps the stable electron and ion transport channels for the electrode materials in the sodium ion batteries and oxygen evolution reactions. The Fe–Co–P/C as anode materials for sodium ion batteries deliver a high discharge capacity of 464 mAh g〈sup〉−1〈/sup〉 at 0.1 A g〈sup〉−1〈/sup〉. After 500 cycles at the current density of 0.5 A g〈sup〉−1〈/sup〉, the capacity of the electrode still retain 293 mAh g〈sup〉−1〈/sup〉, which is attributed to the porous carbon framework to confine the Fe–Co–P in the composites and prevent the Fe–Co–P nanoparticles from aggregating. On the other hand, the Fe–Co–P also exhibit high-efficient performance for oxygen evolution reaction with the overpotential of 151 mV to reach the current density of 10 mA cm〈sup〉−2〈/sup〉, and the Tafel slope of 77.78 mV dec〈sup〉−1〈/sup〉 in 1.0 M KOH. Our research provides a unique carbon substrate material with hierarchical nanostructure and new design stagey for bimetallic phosphide based electrode for sodium ion batteries and electrocatalytic oxygen evolution reactions.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619315051-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Xing Yang, Yiwei Tang, Jiangfeng Zheng, Guozhi Shang, Jian Wu, Yanqing Lai, Jie Li, Zhian Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tailoring the structure of Ni-rich ternary layered cathode is considered as an effective way to solve its poor cycling and rate capability. Herein, a special structure of Ni〈sub〉0.6〈/sub〉Co〈sub〉0.2〈/sub〉Mn〈sub〉0.2〈/sub〉(OH)〈sub〉2〈/sub〉 precursor, in which strips composed of lamellar primary particles are vertically inserted, is rationally designed through feasible industrialized co-precipitation process. Particularly, precursor possesses a loose interior and dense exterior structure by observation of cross section. After sintering, LiNi〈sub〉0.6〈/sub〉Co〈sub〉0.2〈/sub〉Mn〈sub〉0.2〈/sub〉O〈sub〉2〈/sub〉 (NCM622) cathode shows monodispersed microspheres whose external surface is tightly wrapped rod-like primary particles. Moreover, NCM622 microspheres inherits the properties of Ni〈sub〉0.6〈/sub〉Co〈sub〉0.2〈/sub〉Mn〈sub〉0.2〈/sub〉(OH)〈sub〉2〈/sub〉 precursor, displaying hollow structure and aligned primary particles along the radial direction. NCM622 cathode shows optimal electrochemical properties in the voltage window of 2.8–4.4 V. It displays a revisable capacity of 142.4 mAh g〈sup〉−1〈/sup〉 (79.3% for capacity retention ratio) after 300 cycles under current density of 1 C. A reversible capacity of 110.3 mAh g〈sup〉−1〈/sup〉 can be obtained after 500 cycles even at current density of 3 C, and corresponding capacity decay rate is only 0.068% for each cycle. The tailored cathode has great potential applications in batteries of high-power and long calendar life as well as provides an idea for structural design of high nickel cathode.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Xue-Jiao Nie, Xiao-Tong Xi, Yang Yang, Qiu-Li Ning, Jin-Zhi Guo, Mei-Yi Wang, Zhen-Yi Gu, Xing-Long Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the extensive application processes of lithium ion batteries (LIBs), a great quantity of spent LIBs is producing, which is harmful to human and the environment if not handled properly. In addition, due to the scarcity of lithium on earth, sodium with relatively high abundance and low cost is expected to replace lithium. Hence, it is an interesting and urgent work of reusing the spent materials from the end-of-life LIBs for designing sodium-ion batteries (SIBs). Herein, an efficient method is proposed to recycle the spent LiMn〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 and directly reuse it as the cathode of SIBs. As electrochemical tests show, such recycled LiMn〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 delivers excellent Na-storage properties in SIBs. For example, its discharge capacity can gradually increase to 163.2 mAh g〈sup〉−1〈/sup〉 over 50 cycles at 100 mA g〈sup〉−1〈/sup〉, and the highest reversible capacity is up to 176.3 mAh g〈sup〉−1〈/sup〉 at 20 mA g〈sup〉−1〈/sup〉. It is further revealed by combining the electrochemical analyses and 〈em〉ex-situ〈/em〉 characterizations that, the continuous increase of capacity during the initial 50 cycles is due to the phase transition of the spinel into layered structure caused by the Li〈sup〉+〈/sup〉/Na〈sup〉+〈/sup〉 (de)insertion. Studies of electrode kinetics indicate the faster ion diffusion in the layered material than the spinel one. This work provides a new strategy to recycle the spent LIBs, i.e., directly reusing the exhausted electrode materials to the next-generation batteries.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314744-fx1.jpg" width="441" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Weiyi Cao, Kai Han, Mengxun Chen, Hongqi Ye, Shangbin Sang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The practical application of Si anode is still severely hindered owing to its unsatisfactory electrochemical performance, especially including poor initial Coulombic efficiency and long-term cycling stability. In this work, AlSi alloy powder was applied as precusor to prepare micro-sized porous Si. In order to better understand the effect of particle size on both morphology and electrochemical performance, the particle size of AlSi alloy powder was optimized. The results show that the average diameter of micro-sized porous Si with different particle sizes are about 5, 10, 15 μm, respectively. Besides, the initial Coulombic efficiency of micro-sized Si exhibits an increasing trend with the increase of particle size of AlSi alloy powder. The micro-sized porous Si electrode etched from AlSi alloy powder in diameter of 30 μm exhibits an initial Coulombic efficiency of 83.5% and capacity retention of 81.25% after 200 cycles at current density of 1 A g〈sup〉−1〈/sup〉. The results could potentially provide a helpful guide for the scalable fabrication of micro-sized porous Si anode with high initial Coulombic efficiency and long-term cyclibility.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Xiaoye Lu, Minghua Zhou, Yawei Li, Pei Su, Jingju Cai, Yuwei Pan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydrogen peroxide (H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉) is a green oxidant that widely used in environmental remediation and chemical industries, hence the exploration of suitable modified cathode for the cost-effective electrochemical synthesis of H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 is of great importance. In this work, tert-butyl-anthraquinone (TBAQ) was attempted to modify four kinds of typical carbon materials (carbon aerogel, carbon nanotube (CNT), carbon black and graphene-doped carbon black) to fabricate gas diffusion electrode (GDE) to improve H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 production for potential use in electro-Fenton process. It was found that CNT-GDE containing 2% TBAQ had the highest H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 production (150.6 mg/L) with a high current efficiency (95%) and low energy consumption (2.43 kWh/(kg H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉)) among four carbon materials because of the redox of TBAQ and more active sites (C–C sp〈sup〉3〈/sup〉 carbon and oxygen-containing functional groups). The effects of TBAQ addition amount, current and initial pH on H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 performance were investigated. The presence of TBAQ could improve oxygen reduction activity, H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 selectivity and hydrophobicity to improve H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 production. Suitable current (50 mA) and initial pH benefited the enhancement in H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 production. The CNT-GDE containing 2% TBAQ showed better H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 production performance with good stability when comparing with literature, indicating promising for electro-Fenton application.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Dongfei Sun, Xuan Miao, Yijuan He, Li Wang, Xiaozhong Zhou, Guofu Ma, Ziqiang Lei〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Developing advanced electrode materials with hierarchical porous structure is one of the promising strategies to achieve superior properties in lithium-ion batteries (LIBs). Herein, this study reports the design and fabrication of MoS〈sub〉2〈/sub〉 nanosheets @ 3D interconnected porous graphitic carbon anchored on carbonized cotton cloth (CC/PGC@MoS〈sub〉2〈/sub〉) as an anode for LIBs. The uniform interconnected porous PGC@MoS〈sub〉2〈/sub〉 is not only grown on the surface of carbon fibers of CC, but also filled in the spaces among carbon fibers to achieve a dense and interconnected conductive network. The intermediate graphitic carbon network in CC/PGC@MoS〈sub〉2〈/sub〉 nanostructure can greatly enhance the electronic conductivity, provide short ion transport paths and create abundant active sites. Benefiting from its unique structure, the CC/PGC@MoS〈sub〉2〈/sub〉 electrode delivers a high reversible capacity (reversible capacity of 1095.1 mA h g〈sup〉−1〈/sup〉 at 0.1 A g〈sup〉−1〈/sup〉), excellent rate capability, and remarkable cycling stability (reversible capacity of 816 mA h g〈sup〉−1〈/sup〉 at 1.0 A g〈sup〉−1〈/sup〉 after 400 cycles), making it promise as an electrode material for LIBs. This study provides a new strategy for designing carbon-based materials with superior electrochemical properties.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Yayu Guan, Haicheng Xuan, Hongsheng Li, Peide Han〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The MoS〈sub〉2〈/sub〉/NiS–Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉 core-shell structure with flower-like microspheres morphology is a product of reasonable construction on nickel foam. The synergistic effect of heterostructure and abundant active sites make the catalyst exhibits excellent performance in alkaline solution, especially at high current. Specifically, at 200 mA cm〈sup〉−2〈/sup〉 current density, the MoS〈sub〉2〈/sub〉/NiS–Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉 composite exhibits small overpotential of 181 mV and Tafel slope of 70.0 mV dec〈sup〉−1〈/sup〉 for hydrogen evolution reaction, and low overpotential of 460 mV and Tafel slope of 30.3 mV dec〈sup〉−1〈/sup〉 for oxygen evolution reaction. Moreover, MoS〈sub〉2〈/sub〉/NiS–Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉 can run stably for 12 h at 200 mA cm〈sup〉−2〈/sup〉 current density without obvious fluctuation, showing excellent durability. Meanwhile, MoS〈sub〉2〈/sub〉/NiS–Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉 as an electrolyzer achieves a current density of 10 mA cm〈sup〉−2〈/sup〉 at 1.49 V, without decay after a durability test of 12 h. These superior properties of the MoS〈sub〉2〈/sub〉/NiS–Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉 make it become a powerful competitor for the high activity bifunctional non-noble-metal electrocatalysts.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314628-fx1.jpg" width="368" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Jinhui Tong, Wenyan Li, Lili Bo, Yuliang Li, Tao Li, Qi Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, composites of Ni〈sub〉2〈/sub〉P/Ni(PO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉 inlayed in N/S self-doped ultrathin holey carbon nanosheets were facilely prepared using methyl orange (MO) as nitrogen and sulfur sources, in-situ produced Ni(OH)〈sub〉2〈/sub〉 nanosheet by hydrolysis of NiCl〈sub〉2〈/sub〉 as self-sacrificed template, followed by pyrolysis and phosphorization. Ni〈sub〉2〈/sub〉P/Ni(PO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉 was highly dispersed in carbon nanosheets and supplied fruitful of exposed active sites, and thus endowed the as-prepared samples highly electrocatalytic activities for water splitting. In addition, the N/S self-doped carbon protected Ni〈sub〉2〈/sub〉P/Ni(PO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉 from corrosion by the electrolyte and greatly enhanced the stabilities of the catalysts. As a result, the optimized composite 1:8-NPO/NS-C-420, derived from the precursor with 1:8  molar ratio of MO/Ni(II) and phosphorized at 420 °C, has exhibited excellent electrocatalytic activities for hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and overall water splitting. As a result, 88 mV and 273 mV overpotential was obtained for HER and OER at 10 mA/cm〈sup〉2〈/sup〉 in acidic and alkaline electrolyte, respectively. As for the overall water splitting, only 1.63 V of cell voltage is needed to reach 10 mA/cm〈sup〉2〈/sup〉. The catalyst also exhibited high long-term stability in HER, OER and water splitting.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314276-fx1.jpg" width="346" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Meixiu Song, Yanhui Song, Hai Li, Peizhi Liu, Bingshe Xu, Hong Wei, Junjie Guo, Yucheng Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electrochemical catalytic hydrogen evolution reaction is one of the most promising ways to produce hydrogen. Structural optimizing of carbon supports has been proven an effective way to improve the electrocatalytic performance of Pt catalysts. In this work, hierarchically porous carbon prepared by the “bread leavening method” is proved as an excellent substitution for commercial carbon black to support Pt nanoparticles due to its large specific surface area, abundant oxygen-containing functional groups and defect sites. Notably, the Pt catalyst supported on hierarchically porous carbon exhibits an outstanding catalytic performance towards hydrogen evolution reaction in 0.5 M H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 aqueous solution. The overpotential is 24 mV at the current density of −10 mA cm〈sup〉−2〈/sup〉. The composite displays an onset potential of −10 mV, which is much more positive than that of the commercial Pt/C (−18 mV). Furthermore, the composite shows an excellent long-term stability after 2000 cycles and chronoamperometric response for 10 h. This work provides an ideal alternative to the commercial Pt/C to catalyze the electrochemical water splitting.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314513-fx1.jpg" width="356" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Ying Lu, Yicong Chu, Wenzhuo Zheng, Mingxin Huo, Hongliang Huo, Jiao Qu, Hongbin Yu, Yahui Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A visible-light responsive dual photoelectrode photocatalytic fuel cell (PFC) which was consisted of n-type BiVO〈sub〉4〈/sub〉/TiO〈sub〉2〈/sub〉 nanotube (NT) photoanode and p-type Cu〈sub〉2〈/sub〉O/TiO〈sub〉2〈/sub〉 NT photocathode was successfully constructed for hazardous organics decomposition with simultaneous power recovery. The characterization proved the incorporation of BiVO〈sub〉4〈/sub〉 and Cu〈sub〉2〈/sub〉O not only increased the light harvesting efficiency of photoelectrodes but also improved their quantum yield, eventually exhibiting high photoelectrochemical performances. Significantly enhanced removal of tetracycline hydrochloride and electricity generation was obtained in the BiVO〈sub〉4〈/sub〉/TiO〈sub〉2〈/sub〉 NT-Cu〈sub〉2〈/sub〉O/TiO〈sub〉2〈/sub〉 NT PFC system. The rate constant of this dual photoelectrode PFC was 1.42 and 3.66 times as much as that of BiVO〈sub〉4〈/sub〉/TiO〈sub〉2〈/sub〉 NT-Pt PFC and Pt–Cu〈sub〉2〈/sub〉O/TiO〈sub〉2〈/sub〉 NT PFC, respectively, and the maximum power density was 1.68 and 103.8 folds as great as that of BiVO〈sub〉4〈/sub〉/TiO〈sub〉2〈/sub〉 NT-Pt PFC and Pt–Cu〈sub〉2〈/sub〉O/TiO〈sub〉2〈/sub〉 NT PFC. The enhancement was attributed to the large interior bias originated from the Fermi level difference between two electrodes, driving the photoelectrons of BiVO〈sub〉4〈/sub〉/TiO〈sub〉2〈/sub〉 NT to combine with the holes of Cu〈sub〉2〈/sub〉O/TiO〈sub〉2〈/sub〉 NT across external circuit and thus generating electricity. Meanwhile, organics were degraded by the anode holes, cathode electrons, and reactive oxygen species generated via chain reactions. The mechanism analysis confirmed the important roles of cathode electrons and anode holes, either acting as the oxidizing agent or the origination of hydroxyl radicals. Furthermore, the BiVO〈sub〉4〈/sub〉/TiO〈sub〉2〈/sub〉 NT-Cu〈sub〉2〈/sub〉O/TiO〈sub〉2〈/sub〉 NT PFC displayed good stability and reusability.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Aiming at enhancing the hazardous organics decomposition and power recovery, a visible-light responsive dual photoelectrode photocatalytic fuel cell (PFC) consisted of n-type BiVO4/TiO2nanotube (NT) photoanode and p-type Cu2O/TiO2NT photocathode was successfully constructed. The proposed PFC system provided a self-sustained and energy-saving methodology for simultaneous pollutants removal and electricity generation.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314653-fx1.jpg" width="299" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Ali Abdollahi, Amin Abnavi, Shahnaz Ghasemi, Shams Mohajerzadeh, Zeinab Sanaee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Here, controlled growth of vertically aligned carbon nanotubes (VACNTs) on free-standing porous activated reduced graphene oxide (a-rGO) paper was fabricated using plasma-enhanced chemical vapor deposition method. The electrochemical performance of prepared film was investigated to provide effective electrode for 3D flexible high-performance lithium-ion batteries (LIBs) and supercapacitors. The results revealed that the prepared electrode exhibited a high specific capacitance of 347 F/g at 0.5 A/g in 1 M KOH electrolyte, 60% more than non-activated rGO-paper (218 F/g). The VACNTs on a-rGO have increased the accessible surface area and acted as efficient electrical conducting paths, which improved the power density. The free-standing flexible supercapacitor fabricated using such a film exhibited a sufficient electrochemical behaviour with high power density of 407 kW kg〈sup〉−1〈/sup〉 at 5 Wh.kg〈sup〉−1〈/sup〉 at a current density of 0.5 A/g. Since VACNTs with low sp〈sup〉2〈/sup〉 hybridization defect lead to cyclic stability, suitable for high-performance LIB anodes. This 3D flexible anode electrode demonstrated a high initial discharge capacity of 1401 mAhg〈sup〉−1〈/sup〉 with a large reversible charge capacity of 958 mAhg〈sup〉−1〈/sup〉 at 150 mAg〈sup〉−1〈/sup〉. The charge and discharge capacity have reached a stable value of 459 mAhg〈sup〉−1〈/sup〉 after 100 cycles with a coulombic efficiency of ∼100% which is much higher than most carbon structures.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S001346861931446X-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Bo Zhao, Felix Mattelaer, Jeroen Kint, Andreas Werbrouck, Lowie Henderick, Matthias Minjauw, Jolien Dendooven, Christophe Detavernier〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To increase energy density in lithium-ion batteries (LIBs), novel anode materials are considered based on conversion and alloying mechanisms as these typically possess far higher storage capacity than graphite, however, cyclability of these compounds is typically poor. To overcome these issues, ternary or ‘mixed’ compounds are considered. However, the degree of mixing is often overlooked. Here, Atomic layer deposition (ALD) is used to investigate the influence of the degree of mixing, composition and crystallinity of ZnO–SnO〈sub〉2〈/sub〉 ternary materials as LIB anodes. Firstly, two different mixing nanostructures of thin-film ZnO–SnO〈sub〉2〈/sub〉 electrodes are constructed: atomically intermixed films where the Zn, Sn and O are mixed at the atomic scale in a single amorphous layer, and nanolaminated films where the ZnO layer and SnO〈sub〉2〈/sub〉 layers form a structure with well-defined interfaces. Secondly, by tuning the ratio of ZnO and SnO〈sub〉2〈/sub〉, different compositions are obtained. Finally, when ZnO–SnO〈sub〉2〈/sub〉 composite films are annealed post-deposition, these can be crystallized to form Zn〈sub〉2〈/sub〉SnO〈sub〉4〈/sub〉 films. The electrochemical performances of these different variations of ternary ZnO–SnO〈sub〉2〈/sub〉 composites were investigated as anode materials in LIBs. This demonstrated the potential of ALD as a research tool in LIBs research and revealed the importance of atomic scale intermixing in these ternary oxides as anodes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉ALD enables precise control over the structure, composition, and crystallinity of materials. The degree of mixing proves the critical parameters of the battery performance of composite electrodes.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314525-fx1.jpg" width="421" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Karolina Cysewska, Jakub Karczewski, Piotr Jasiński〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, the spontaneous release of anti-inflammatory salicylate from polypyrrole (PPy) coated iron has been studied during degradation of the material in phosphate buffer saline at 37 °C. The sodium salicylate was incorporated into PPy in a one-step electropolymerization process. The influence of the synthesis conditions such as sodium salicylate concentration, pyrrole concentration and deposition charge on drug release profile has been investigated. The morphology, surface roughness and redox properties of PPy/Fe have been also studied. The drug release was studied by UV–Vis spectrophotometer with flow cuvette connected to the electrochemical cell, which provided continuous study of the released dopant. As a result, reliable and quantitative study of salicylate release from PPy coated iron was attained. Depending on the synthesis conditions the concentration of the salicylate released was in the range of 83–183 μM cm〈sup〉−2〈/sup〉 after 21 h of immersion. The rate of drug release of 10–11 μM h〈sup〉−1〈/sup〉 was the highest at the beginning after immersion (1–2 h), then it gradually decreased and finally it reached the lowest value of approximately 0.3 μM h〈sup〉−1〈/sup〉 at the end of the process.”〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Wei Gao, Chen Wang, Fangyuan Ma, Dan Wen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Efficient anodic electrocatalysts are of great importance for the water and urea electrolysis to lower the overall potential for hydrogen generation. NiMoO〈sub〉4〈/sub〉 is recently considered as a promising electrocatalyst towards water and urea oxidation reactions while its catalytic properties are still not comparable to the state-of-the-art catalysts. Herein, decorating CeO〈sub〉2〈/sub〉 nanoparticles on NiMoO〈sub〉4〈/sub〉 nanosheets is proposed and realized by the facile post-annealing treatment of NiMoO〈sub〉4〈/sub〉 with absorbed Ce〈sup〉3+〈/sup〉 ions. Due to the strong interaction between CeO〈sub〉2〈/sub〉 and NiMoO〈sub〉4〈/sub〉, the surface chemical states are modulated with more defects as catalytic sites. By optimizing the ratio of CeO〈sub〉2〈/sub〉 to NiMoO〈sub〉4〈/sub〉, the obtained catalyst of CeO〈sub〉2〈/sub〉 modified NiMoO〈sub〉4〈/sub〉 exhibited significantly enhanced activity with lower overpotentials and remarkable durability as compared with NiMoO〈sub〉4〈/sub〉 for water and urea oxidation. Therefore, this facile method of post decorating CeO〈sub〉2〈/sub〉 nanoparticles promoted the activity of NiMoO〈sub〉4〈/sub〉, contributing to the robust anodes for low-cost and stable hydrogen generation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Mana Iwai, Tatsuya Kikuchi, Ryosuke O. Suzuki, Shungo Natsui〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electrochemical and morphological characterization of the porous alumina formed by galvanostatic anodizing in etidronic acid under various operating conditions was performed. High-purity aluminum plates were anodized in 0.03–3 M etidronic acid solutions at 273–333 K and 0.25–500 Am〈sup〉−2〈/sup〉 for up to 24 h. Galvanostatic anodizing in etidronic acid operated over a wide range voltage measuring from a few V to 246 V. The time required for the steady growth of porous alumina not only depends on the current density but also the temperature and the concentration of the electrolyte solution during galvanostatic anodizing. The average, maximum, and minimum cell sizes of the porous alumina were directly proportional to the anodizing voltage with a proportionality constant of 2.5, 3.5 and 0.7, respectively, and were independent of other parameters. The number density of the cell was also a function of the anodizing voltage and agreed with the theoretical value obtained for ordered porous alumina with an ideal honeycomb distribution. The maximum voltage measured during galvanostatic anodizing was linearly proportional to the plateau voltage with a proportionality constant of 1.4.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314549-fx1.jpg" width="259" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Linh Duy Nguyen, Tung Son Vinh Nguyen, Tien Minh Huynh, Robert Baptist, Tin Chanh Duc Doan, Chien Mau Dang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A sputtered platinum thin film was fabricated by using photolithography, sputtering, and a lift-off method. The sputtered Pt grains were uniformly dispersed in the film as observed from FE-SEM images to form a compact film with fairly homogeneous size. Square wave voltammetry was used to directly detect Fe(III) with this electrode, typically at a working potential of 0.63 V (vs. Ag/AgCl). The method had a 90 ppb detection limit and worked in the 0.3–5 ppm concentration range. This value meets the requirements set by the World Health Organization. In addition, the stability and reproducibility of the electrode were superior (with RSDs of 3.363% for 5 repetitive measurements). For real tap and well water samples, the electrode gave the well-defined peak for Fe(III) without showing any enrichment in Fe(III). The results from real water analyses were in agreement with those obtained by the UV–Vis method.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Motoyuki Hirooka, Tomohito Sekiya, Yoshitomo Omomo, Masayuki Yamada, Hideaki Katayama, Takefumi Okumura, Yusuke Yamada, Kingo Ariyoshi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lithium-ion batteries (LIBs) consisting of LiCoO〈sub〉2〈/sub〉 and graphite electrodes exhibit a trade-off relationship between their reversible capacity and cycle/calendar life in terms of the charge cut-off voltage. That is to say, a higher charge cut-off voltage leads to a larger reversible capacity and shorter cycle life. In order to develop LIBs that satisfy both performance criteria (i.e., have a high reversible capacity as well as a long cycling life), the degradation mechanism of the LiCoO〈sub〉2〈/sub〉 electrode under float charge conditions and high temperatures is investigated while focusing on the relationship between the structural deterioration of the electrode and capacity fading. Durability tests performed on graphite/LiCoO〈sub〉2〈/sub〉 cells under float charge conditions (4.4 V at 60 °C) induced a drop in the open-circuit voltage as well as capacity fading in the LiCoO〈sub〉2〈/sub〉 electrode along with the dissolution of a large number of cobalt ions. Acoustic emission histometry, X-ray diffraction, and transmission electron microscopy analyses of the LiCoO〈sub〉2〈/sub〉 electrode after the float charge tests revealed that the degradation of the LiCoO〈sub〉2〈/sub〉 electrode during the float charge tests occurred as per the following steps: (1) the HF generated by the decomposition of LiPF〈sub〉6〈/sub〉 reacts with the charged LiCoO〈sub〉2〈/sub〉 electrode, (2) the charged LiCoO〈sub〉2〈/sub〉 electrode is disproportionated into CoO〈sub〉2〈/sub〉 and Co〈sup〉2+〈/sup〉 ions, and finally (3) the CoO〈sub〉2〈/sub〉 having an O1 structure decomposes into cobalt oxides containing cobalt ions in a lower oxidation state, which is associated with the evolution of oxygen gas.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Chaozhi Kuang, Yanbin Xu, Weikang Lai, Guangyan Xie, Zhanchang Pan, Li Zheng, Manjunatha P. Talawar, Jiayin Ling, Shengjun Ye, Xiao Zhou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉With the rapid development of livestock industry, a large amount of livestock wastewater generates in China in recent years. The conventional treatment process for livestock wastewater, including anaerobic digestion and anoxic-oxic treatment, is very common in China for the low operational cost. However, the very low BOD〈sub〉5〈/sub〉/COD〈sub〉Cr〈/sub〉 ratio (〈0.1) in the associated effluent renders the further treatment process very difficult. In this study, a PbO〈sub〉2〈/sub〉 anode coupled with a 2-ethylanthraquinone (EAQ)-modified graphite felt cathode was used to treat the livestock wastewater (BOD〈sub〉5/〈/sub〉COD〈sub〉Cr〈/sub〉 〈 0.1) discharged from the conventional two-stage anoxic/oxic (A/O) process. The results of scan electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and fourier transforminfrared spectroscopy (FTIR) show that the prepared PbO〈sub〉2〈/sub〉 electrode has a smaller crystal size, higher oxygen evolution reaction (OER) potential and an excellent electro-catalytic performance compared to a purchased PbO〈sub〉2〈/sub〉 electrode, and the EAQ-modified graphite felt cathode has a higher content of oxygen-containing functional groups and higher oxygen reduction reaction (ORR) electro-catalytic performance than pristine graphite felt. The results of the electrolysis experiment showed that the BOD〈sub〉5〈/sub〉/COD〈sub〉Cr〈/sub〉 ratio was increased from 0.084 to 0.42 with 71.5% COD〈sub〉Cr〈/sub〉 removal after 80 min of electrolysis, when the Fe〈sup〉2+〈/sup〉 concentration was 0.3 mM. The 〈sup〉.〈/sup〉OH produced in the electrolysis system was captured successfully by electron paramagnetic resonance (EPR).〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314537-fx1.jpg" width="298" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Mengting Liu, Panpan Jing, Ting Wang, Xiaoyi Hou, Michael Liu, Zifei Sun, Junshuai Li, Deyan He〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sodium-ion batteries (SIBs) have attracted extensive interests for the large electronic equipment. Increased size of the Na-ion is the primary factor of its slow diffusion in the bulk, which poses big challenges for the manufacturing of active materials suitable for SIBs. Here, we present a set of porous Co〈sub〉0.85〈/sub〉Se/N-doped carbon (Co〈sub〉0.85〈/sub〉Se/NC) composites with an excellent ratio (above 85%) of surface/near-surface pseudocapacitance Na-ion phenomena. When cycled at 100 mA g〈sup〉−1〈/sup〉, the Co〈sub〉0.85〈/sub〉Se/NC-1.0 anode delivers an ultrahigh initial discharge capacity of 713 mAh g〈sup〉−1〈/sup〉. During the 100 cycles under 1000 mA g〈sup〉−1〈/sup〉, its reversible specific capacity is up to 509 mAh g〈sup〉−1〈/sup〉. Besides, the anode also presents a robust rate performance with a limited capacity loss between 100 and 5000 mA g〈sup〉−1〈/sup〉. Especially, a capacity of 382.8 mAh g〈sup〉−1〈/sup〉 is still delivered at 5000 mA g〈sup〉−1〈/sup〉. Among the various cobalt selenide-based materials, such an outstanding Na〈sup〉+〈/sup〉 storage capacity and rate performance contribute the Co〈sub〉0.85〈/sub〉Se/NC composites to be a promising candidate of SIBs.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619315026-egi10S02L88SSM.jpg" width="500" alt="Image 100288" title="Image 100288"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Yade Zhu, Ying Huang, Chen Chen, Mingyue Wang, Panbo Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, phosphorus-doped porous carbon was obtained via a simple method with leaves as raw materials, and its broad application prospects in sodium-ion and lithium-ion battery were proved. The effect of different mass ratios on microstructure and properties were investigated. Phosphorus-doped porous carbon has high specific surface area and pore volume, which is favorable for contact with electrolyte and transportation of electron/ion. Meanwhile, doping of phosphorus increases layer spacing of carbon lattice and enhances adsorption of sodium ion, which are more conducive to the storage of sodium ions. Based on above advantages, PC-3 has stable and fast sodium-ion and lithium-ion storage performance with capacity of 310.4 mAh g〈sup〉−1〈/sup〉 for sodium-ion battery and 723.4 mAh g〈sup〉−1〈/sup〉 for lithium-ion battery after 200 cycles. Furthermore, carbonization temperature of this method is lower than other reports, saving energy and having better practical value.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Winda Devina, Dongho Nam, Jieun Hwang, Christian Chandra, Wonyoung Chang, Jaehoon Kim〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hierarchically porous anatase TiO〈sub〉2〈/sub〉 microparticles are synthesized in supercritical methanol (scMeOH) in the presence of organic surface modifiers such as oleylamine, oleic acid, and poly(ethylene glycol)methyl ether/citric acid (PEGME/CA) mixture. Primary TiO〈sub〉2〈/sub〉 nanoparticles (5–9 nm) that loosely aggregate to form secondary micron-sized particles (0.2–1.5 μm) are obtained in the presence of PEGME/CA. The surface modifier aids the effective suppression of undesirable crystal growth because their molecules cap the surfaces of growing particles in scMeOH. An ultrathin, conformal and uniform carbon layer with 1–2 nm thickness is then formed on the surface of the TiO〈sub〉2〈/sub〉 particles by heat treatment. The carbon-coated TiO〈sub〉2〈/sub〉 particles delivers 231 mAh g〈sup〉−1〈/sup〉 at 0.1 C after 50 cycles and 85 mAh g〈sup〉−1〈/sup〉 at 10 C in a lithium-ion battery cell, 275 mAh g〈sup〉−1〈/sup〉 at 0.1 C after 50 cycles, 40 mAh g〈sup〉−1〈/sup〉 at 10 C, and high capacity retention of 94% after 450 cycles in a sodium-ion battery cell. The excellent electrochemical performance of the TiO〈sub〉2〈/sub〉 particles is attributed to the small crystallite size, continuous electronic network formed by the close contact of individual carbon-coated primary TiO〈sub〉2〈/sub〉 particles, and the effective penetration of the mesopores by the electrolytes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314987-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Maryam Sadehvand, Ahmad Amiri, Farzaneh Fadaei Tirani, Jun Gu, Kurt Schenk-Joß〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Two dicopper (II) complexes of general formula [CuLX〈sub〉2〈/sub〉]〈sub〉2〈/sub〉 {L = 2, 5-diphenyl-3, 4(2-pyridyl) cyclopenta-2, 4-dien-1-one, X = Cl (〈strong〉1〈/strong〉) or Br (〈strong〉2〈/strong〉)} have been synthesized and characterized by elemental analysis, IR, UV–Vis spectroscopic methods. The crystal structures of both complexes have been determined by single-crystal X-ray diffraction; 〈strong〉1〈/strong〉 and 〈strong〉2〈/strong〉 have binuclear structures and Cu (II) centres in both complexes adopt a distorted square pyramidal geometry. Two [CuLX] (X = Cl or Br) units in both complexes are linked via μ-X coordination bridge modes with the Cu–Cu distances of 3.534 and 3.716 Å for 〈strong〉1〈/strong〉 and 〈strong〉2〈/strong〉 respectively. The electrochemical behaviour of the free L ligand and the corresponding Cu (II) complexes was studied in acetonitrile. The cyclic voltammetry of the complexes 〈strong〉1〈/strong〉 and 〈strong〉2〈/strong〉 show three ligand based reduction processes and two metal-centred reductions that are assigned to copper (II) to copper (I) and copper (I) to copper (0). The electrocatalytic activity for the reduction of CO〈sub〉2〈/sub〉 of the two complexes was investigated; both complexes are active for the CO〈sub〉2〈/sub〉 reduction and result in the formation of CO.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Afzal Shah, Anum Nisar, Khalid Khan, Jan Nisar, Abdul Niaz, Muhammad Naeem Ashiq, Mohammad Salim Akhter〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Mercury and thallium forms a eutectic alloy that finds extensive use in thermostatic devices owing to its capability of withstanding extremely low temperature. As both these metals are highly toxic, so herein we report their co-sensing on a sensitive electrochemical platform. The performance of the designed sensing surface was tested by electrochemical impedance spectroscopy, cyclic voltammetry, square wave anodic stripping voltammetry and chronocoulometry. The fabricated electrode successfully discriminated the signals of mercuric and thallium ions in the same voltammogram without any issue of peaks overlapping. The electrode was found stable, sensitive to mercuric and thallium ions and resistant to interfering non-target metal ions at the voltammetric potential of target analytes. The role of the modifier in facilitating electron transfer between host (electrode) and guest (target metal ions) was ensured from the more intense signals at the modified electrode compared to bare glassy carbon electrode (GCE). The mediator performance of the modifier in bringing the analyte closer to the transducer was also supported by computational findings of strong interaction between the amino acid, glycine and metal ions. Under optimized conditions, the glycine modified GCE sensed mercury and thallium ions to a concentration level well below their danger limit set by the Environmental Protection Agency of USA. The cost effective, greener approach, rapid responsiveness and portable characteristics of the designed electrode suggest its practicability for the simultaneous trace level detection of thallium and mercury ions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Long Pan, Haijian Huang, Tian Liu, Markus Niederberger〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electrode materials that combine the high energy density of batteries and the high power density of supercapacitors become an increasing need for current and near-future applications. Ta〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 delivers a high theoretical capacity but suffers from unsatisfactory rate capabilities. Here we prepare a structurally disordered Ta〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 nanoparticle aerogel via a nonaqueous sol-gel process followed by CO〈sub〉2〈/sub〉 super-critical drying. The resulting aerogels exhibit large surface area, high porosity, fast ion diffusion, and extrinsically pseudocapacitive Li〈sup〉+〈/sup〉/Na〈sup〉+〈/sup〉 storage behavior (through surface redox reactions). With these merits, when evaluated as anode material for both lithium-ion and sodium-ion half cells (LIBs and NIBs), the Ta〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 aerogels show excellent rate capabilities (97.0 and 43.7 mA h g〈sup〉−1〈/sup〉 at 5000 mA g〈sup〉−1〈/sup〉 for LIBs and NIBs, respectively) and highly stable cycling performance (20000 cycles at 5000 mA g〈sup〉−1〈/sup〉 and 10000 cycles at 1000 mA g〈sup〉−1〈/sup〉 without obvious capacity fading for LIBs and NIBs, respectively). This work introduces Ta〈sub〉2〈/sub〉O〈sub〉5〈/sub〉, a typical conversion-type metal oxide without intrinsic pseudocapacitance, as a promising anode material with high extrinsic pseudocapacitance for both LIBs and NIBs, which may open the door to achieve high-rate alkali-ion storage with low synthesis cost for durable microbatteries.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Aerogels composed of a 3-dimensional network of structurally disordered Ta〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 nanoparticles are proposed and realized for high rate and highly stable Li-ion and Na-ion storage.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S001346861931504X-fx1.jpg" width="477" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Weijun Zhou, Jizhang Chen, Cuilan He, Minfeng Chen, Xinwu Xu, Qinghua Tian, Junling Xu, Ching-Ping Wong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Thanks to low cost and high safety, aqueous zinc-ion batteries (AZIBs) are attractive candidates for large-scale energy storage applications, while suitable cathode materials are needed urgently. In this work, δ-Na〈sub〉x〈/sub〉V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉·nH〈sub〉2〈/sub〉O with a large interlayer spacing of 10.6 Å is reported as the cathode material for aqueous zinc-ion batteries for the first time. It is found that δ-Na〈sub〉x〈/sub〉V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉·nH〈sub〉2〈/sub〉O performs better than Na〈sub〉2〈/sub〉V〈sub〉6〈/sub〉O〈sub〉16〈/sub〉·nH〈sub〉2〈/sub〉O under the same condition, and its electrochemical performances can be significantly improved after hybridizing it with reduced graphene oxide. The obtained nanocomposite can deliver high reversible capacity of 433.5 mAh g〈sup〉−1〈/sup〉 at 0.1 A g〈sup〉−1〈/sup〉, superior rate capability of 244.1 mAh g〈sup〉−1〈/sup〉 at 5 A g〈sup〉−1〈/sup〉, and good cyclability of 70.5% over 1000 cycles. Such great performances origin from the synergetic effect of δ-Na〈sub〉x〈/sub〉V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉·nH〈sub〉2〈/sub〉O and graphene, which enables rapid Zn〈sup〉2+〈/sup〉 diffusion and large capacitive contribution. Besides, the ex-situ measurement results demonstrate good structural stability and reversible Zn〈sup〉2+〈/sup〉 ion storage behavior of reduced graphene oxide/δ-Na〈sub〉x〈/sub〉V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉·nH〈sub〉2〈/sub〉O nanocomposite. This work extends the knowledge into the material technology of AZIBs.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619315609-fx1.jpg" width="398" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Chih-Yu Lai, Jui-Hong Weng, Wei-Li Shih, Lin-Chi Chen, Chia-Fu Chou, Pei-Kuen Wei〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Impedimetric sensing using interdigitated array (IDA) electrodes usually encounters an analytical problem. Finite diffusion of redox species dominates at low frequencies and confuses researchers, making incorrect understanding of underlying phenomena possible. In this work, an integral equation for calculating the diffusion impedance of IDA electrodes is derived using conformal mapping and cylindrical finite length approximation. Electrodes of different bandwidths and gap widths are fabricated, and their heights and symmetric electrochemical characteristics are verified. Simulations are performed to verify the predicted constant concentration contours. The calculated zero-frequency impedance showed high correlation with the reciprocal of limiting current calculated from literature study (R〈sup〉2〈/sup〉 = 0.992) and from chronoamperometry experiments (R〈sup〉2〈/sup〉 = 0.970). Further evidence for the correctness of theory is established due to the fact that experimental EIS data and calculated impedances are highly consistent (R〈sup〉2〈/sup〉 ≥ 0.948 for real and imaginary part). This sheds some light on explaining the diffusion phenomenon of impedance using IDA electrodes in the low frequency spectrum. An equivalent circuit fitting program is further designed for fitting several elements including the IDA electrode diffusion impedance derived in the theory. The program succeeded to accurately fit the EIS data (average MSE = 0.611), which using the Warburg element failed (average MSE = 54.86). Parameters such as the ratio of electrode bandwidth to gap width and diffusion coefficient can also be determined by fitting the data from a single EIS experiment. Another impedance calculation program is also given, which can aid researchers in relevant fields to model their systems more accurately.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Tankiso Lawrence Ngake, Johannes H. Potgieter, Jeanet Conradie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The electronic and electrochemical properties are reported here for the first time for a series of five tris(β-ketoiminato)ruthenium(III) complexes. Since the β-ketoiminato ligand is unsymmetrical, both 〈em〉fac〈/em〉 and 〈em〉mer〈/em〉 isomers are theoretically possible for these octahedral complexes. Density functional theory calculations show that for complexes containing an H on the imino position, both the 〈em〉fac〈/em〉 and 〈em〉mer〈/em〉 are energetically possible, while for complexes with a Ph on the imino position, the 〈em〉mer〈/em〉 isomer is energetically favoured, due to the steric hindrance caused by the Ph group in the 〈em〉fac〈/em〉 isomer. Electrochemistry, utilizing cyclic voltammetry, showed Ru〈sup〉III/IV〈/sup〉 oxidation, Ru〈sup〉III/II〈/sup〉 reduction, as well as ligand based reduction of the Ru〈sup〉II〈/sup〉 complex. Different Ru〈sup〉III/IV〈/sup〉 and Ru〈sup〉III/II〈/sup〉 redox couples were observed for the different 〈em〉fac〈/em〉 and 〈em〉mer〈/em〉 isomers of the tris(β-ketoiminato)ruthenium(III) complexes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Electrochemical and computational chemistry study of the 〈em〉fac〈/em〉 and 〈em〉mer〈/em〉 isomers of tris(β-ketoiminato)ruthenium(III) complexes: 〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S001346861931494X-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Zhenwen Zou, Guang-Ling Song, Zi Ming Wang, Dajiang Zheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A single wire-electrode AC probe was developed to simultaneously and rapidly detect the polarization resistance, capacitance and totally accumulated change of metal resistance that can normally be obtained separately by EIS and a resistance sensor. After being successfully verified in different solutions, this single wire-electrode AC probe was employed to monitor the multi electrochemical parameters and corrosion behavior of pure Fe in 3.5% NaCl solution at room temperature and 95 °C. The results indicated that this method could reliably monitor the variation of instantaneous corrosion rate and accumulated corrosion damage without using a reference or counter electrode.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Krzysztof Nowacki, Maciej Galiński, Izabela Stępniak〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Chitosan-based membranes were formed by a casting method from a CS (chitosan) acetic acid solution, and then modified. Sodium hydroxide (NaOH) and glutaraldehyde (GA) solutions were used as covalent or ionic crosslinking agents respectively. The physicochemical properties of crosslinked CS membranes were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Changes in surface hydrophilicity as a result of the crosslinking process were investigated by means of contact angle measurements. In addition, for both modified and unmodified CS membranes, tensile and electrolyte solution swelling ratio tests were performed. All of the obtained chitosan-based membranes were used in electric double layer capacitor (EDLC) cells to study their applicability as gel electrolytes and membranes. 2 M LiOAc (lithium acetate) water solution was used as an electrolyte in the EDLC cells. Electrochemical characteristics of EDLC cells containing chitosan membranes were determined by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) methods. The results show that the CS crosslinking agent type may improve the mechanical properties and limit electrolyte absorption by the membranes. All tested EDLC cells with CS membranes exhibited very good electrochemical performance. The specific capacitances for EDLC cells with modified chitosan (CS) membranes are equal 106 F g〈sup〉−1〈/sup〉 after the 10 000〈sup〉th〈/sup〉 discharge cycle for both CS/GA and CS/NaOH capacitor cells.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Juan Liu, Tingjiao Xiong, Tao Liu, Chao Yang, Honghui Jiang, Xiaocheng Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Binary metal oxides have been proved to possess better pseudocapacitive performance than single metal oxide analogies. Substitution of toxic and high-cost ions (Co and Mo) in binary metal oxides with low-cost and environmentally-friendly ions (Ni and Mn) is of great economic and environmental importance. In this paper, murdochite-type binary metal oxides (i.e., Ni〈sub〉6〈/sub〉MnO〈sub〉8〈/sub〉) and binary metal oxides@carbon nanotubes (i.e., Ni〈sub〉6〈/sub〉MnO〈sub〉8〈/sub〉@CNTs) core-shell structure were synthesized via a facile hydrothermal approach followed by a calcination process. Electrochemical measurement results indicated that the synthesized Ni〈sub〉6〈/sub〉MnO〈sub〉8〈/sub〉@CNT core-shell structure showed a high specific capacitance of 1213 F g〈sup〉−1〈/sup〉 at 1 A g〈sup〉−1〈/sup〉 with two times capacitance value of Ni〈sub〉6〈/sub〉MnO〈sub〉8〈/sub〉 at same current density. Even at the high current density of 20 A g〈sup〉−1〈/sup〉, the Ni〈sub〉6〈/sub〉MnO〈sub〉8〈/sub〉@CNT core-shell structure can still deliver a high capacitance value of 711 F g〈sup〉−1〈/sup〉, which value is also much higher than that of Ni〈sub〉6〈/sub〉MnO〈sub〉8〈/sub〉 at the current density of 1 A g〈sup〉−1〈/sup〉. With the prepared Ni〈sub〉6〈/sub〉MnO〈sub〉8〈/sub〉@CNT hybrid as positive electrode and activated-polyaniline-derived-carbon as negative electrode, an asymmetric supercapacitor cell (ASC) was successfully assembled. The assembled ASC device exhibited excellent pseudocapacitive performance with a high specific capacitance of 154 F g〈sup〉−1〈/sup〉 at 1 A g〈sup〉−1〈/sup〉 and a high energy density of 58.2 Wh kg〈sup〉−1〈/sup〉 at a power density of 831.4 W kg〈sup〉−1〈/sup〉. Even at a high power density of 16.6 kW kg〈sup〉−1〈/sup〉, the ASC device can still deliver a high energy density of 23.1 Wh kg〈sup〉−1〈/sup〉, suggesting the promising applications of Ni〈sub〉6〈/sub〉MnO〈sub〉8〈/sub〉@CNT hybrid in supercapacitors.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Ivan S. Filimonenkov, Corinne Bouillet, Gwénaëlle Kéranguéven, Pavel A. Simonov, Galina A. Tsirlina, Elena R. Savinova〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Carbon materials are widely applied as conductive additives in studies of the oxygen evolution reaction (OER) in alkaline media catalyzed by transition metal oxides. In this work we investigate the anodic behavior of three representative carbon materials: furnace black (Vulcan XC-72R), acetylene black, and pyrolytic carbon of the Sibunit family (Sibunit-152), in 1 M NaOH at high potentials (ranging from the OER onset and up to 〈em〉ca〈/em〉. 2 V vs. RHE) in the time span from several minutes to several hours. We apply the rotating ring-disk electrode (RRDE) to separate the OER current from the carbon corrosion current. We then use transmission electron microscopy (TEM) to visualize changes in the carbon morphology resulting from corrosion. Finally, we study the OER performance of composite electrodes comprising carbon materials mixed with a La〈sub〉0.5〈/sub〉Sr〈sub〉0.5〈/sub〉Mn〈sub〉0.5〈/sub〉Co〈sub〉0.5〈/sub〉O〈sub〉3−δ〈/sub〉 perovskite OER catalyst, and discuss possible influence of the oxide on the carbon corrosion.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Yu Kang Shen, You Yin Lv, Zhao Jie Huang, Hong Zhong Chi, Feng Yan, Xing Duan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electrodepositing manganese oxide in a three-dimensional graphene architecture has barely been explored, and therefore an exploratory but systematic investigation was conducted. A series of manganese oxide/graphene hydrogel electrodes were prepared by galvanostatic technique. The effects of electrodeposition condition, including current density, deposition time, Mn〈sup〉2+〈/sup〉concentration and bath temperature, on the morphology and capacitive performance of the deposits were investigated. Nucleation and growth processes of the deposited manganese oxide were then deduced. An optimal capacitance of 452.5 F g〈sup〉−1〈/sup〉 was got. This study could provide insight into the crystallization mechanism for electrochemical preparation of MnO〈sub〉x〈/sub〉/graphene electrode for advanced energy storage/conversion devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Yubo Zhao, Yuyan Zhang, Pei Tian, Lei Wang, Kexun Li, Cuicui Lv, Bolong Liang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, novel nitrogen-rich mesoporous carbons (NKZCs) were synthesized with the zeolitic imidazolate framework-8 (ZIF-8) assisted with urea and KOH as the precursors for efficient capacitive deionization (CDI). The deionization tests showed that the NKZCs electrodes had an electrosorption capacity of 31.30 mg g〈sup〉−1〈/sup〉 for 1000 mg L〈sup〉−1〈/sup〉 NaCl solution at 1.2 V, higher than those of carbons obtained from the ZIF-8/KOH composite (20.29 mg g〈sup〉−1〈/sup〉) and single ZIF-8 (17.18 mg g〈sup〉−1〈/sup〉). Besides, there was no significant decrease of the electrosorption capacity after 50 adsorption-regeneration cycles, indicating the excellent recyclability of the NKZCs electrodes. The material and electrochemical measurements revealed that the enhanced CDI performance of the NKZCs electrodes was ascribed to the superior mesoporous structure and rich nitrogen content which not only facilitated the ion transportation but also improved the electrical conductivity and hydrophilicity of the NKZCs. In a conclusion, the NKZCs would be a promising material for application in the CDI.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Nitrogen-rich mesoporous carbons derived from zeolitic imidazolate framework-8 was designed for high-capacity capacitive deionization.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619315336-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Jiří Kaleta, Ludmila Šimková, Alan Liška, Daniel Bím, Jenica M.L. Madridejos, Radek Pohl, Lubomír Rulíšek, Josef Michl, Jiří Ludvík〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Eleven fluorinated 1,3-diphenylisobenzofurans, materials that are promising to perform efficient singlet fission, have been synthesized and their electrochemical reduction and oxidation in non-aqueous dimethylformamide examined. The redox properties are not changed continuously with increasing number of fluorine substituents but there are some qualitative turns in behavior for specific types of substitution revealing a discontinuity requiring deeper investigation. The DFT calculations confirm the trends observed experimentally by correlation of experimental and calculated data. The differences between the geometries of the neutral species and their radical ions were computed and rationalized.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619315270-fx1.jpg" width="318" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Verónica Poza-Nogueiras, Marta Pazos, M. Ángeles Sanromán, Elisa González-Romero〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Concern about the current pollution of water environments and the inefficacy of conventional water treatments for the elimination of refractory contaminants has placed electrochemistry in the spotlight. With the objective of demonstrating the diverse applications that electrochemical techniques can have in the area of water remediation, this study is focused on the use of three different methods: (i) electro-Fenton process with heterogeneous catalyst as the treatment for the degradation of the target compounds; (ii) cyclic voltammetry for the characterization of the electrochemical system, and (iii) differential pulse voltammetry for the monitoring of the evolution of the degradation process. Four organic compounds were selected as target pollutants: the ionic liquid 1,3-Bis(2,4,6-trimethylphenyl)imidazolinium chloride, Mesitol, Mesidine and 2,5-Xylidine. Results were corroborated and complemented with chromatographic and total organic carbon (TOC) measurements. After 420 min of heterogeneous electro-Fenton treatment, almost 80% of TOC abatement was achieved for the ionic liquid and more than 90% for Mesitol, Mesidine and 2,5-Xylidine. Cyclic voltammetry studies for Mesitol and Mesidine suggested the formation of a polymeric film which remains adsorbed on the electrode surface. Finally, it was possible to conclude that the coupling of differential pulse voltammetry with the heterogeneous electro-Fenton process provides useful information about the evolution of the degradation process of pollutants in just a couple of minutes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314859-fx1.jpg" width="295" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Shaofei Zhang, Zhijia Zhang, Jianli Kang, Qin Huang, Zhenyang Yu, Zhijun Qiao, Yida Deng, Jianxin Li, Wei Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In response to the severe blocks of the large volume change and sluggish capacity decay originating from the Lithium ion insertion/extraction in the anodes of Lithium ion batteries, transition metal oxides with high cycle stability are desirable yet extremely challenging for achieving high energy density anodes. Here, we report that a double-shelled NiO nanocrystal-doped MnO layer with robust defects, epitaxially grown on a nanoporous Ni network by simultaneously dealloying and oxidising NiMn alloy, can overcome these challenges to deliver a large capacity with excellent cycle stability. The interconnected core-shell nanoporous structure with robust defects possesses ultrahigh efficient electron/ion transport and a volume buffer. Consequently, the free-standing electrode as a whole delivers a highly reversible capacity of 1172 mAh cm〈sup〉−3〈/sup〉 (960 mAh g〈sup〉−1〈/sup〉) with a remarkable cycle life (105% retention after 200 cycles at 100 mA g〈sup〉−1〈/sup〉). Furthermore, the electrode achieves a high capacity of 831.5 mAh cm〈sup〉−3〈/sup〉 (681 mAh g〈sup〉−1〈/sup〉) even at 1000 mA g〈sup〉−1〈/sup〉, demonstrating a high rate capability. The proposed synthetic strategy can be further explored for the construction of other three-dimensional metal@metal oxide electrodes for application in next-generation energy storage systems.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Changding Wang, Yifan Sun, Enlin Tian, Dongmei Fu, Min Zhang, Xiaojuan Zhao, Weichun Ye〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Compared with 2D metallic Ni〈sub〉3〈/sub〉N nanosheets as a potential alternative to Pt-based catalyst, Ni〈sub〉3〈/sub〉N nanoparticles exhibit inert electrocatalytic hydrogen evolution reaction (HER) activity due to their poor conductivity. In this work, we demonstrated that the HER activity of inert Ni〈sub〉3〈/sub〉N nanoparticles could be significantly improved through high dispersion of trace-loaded Pt on their surface. In detail, Ni〈sub〉3〈/sub〉N/Ni@C with controllable Ni content was prepared via the urea-urea-glass-route by controlling the calcination temperature and time based on the thermal unstability of Ni〈sub〉3〈/sub〉N. Followed by the galvanic replacement between Ni and a platinum precursor, Ni〈sub〉3〈/sub〉N/Ni@C decorated with a trace amount (0.45 wt%) of Pt was simply prepared. The trace-loaded catalyst exhibited greatly enhanced HER activity and stability in entire pH range including in 0.5 M H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉, 1.0 M KOH and 0.2 M PBS (pH = 7), which could be comparable to commercial Pt/C (20 wt%) catalyst. For example, they held low overpotential of 117 mV at 10 mA/cm〈sup〉2〈/sup〉, small Tafel slope of 47.3 mV/dec, and large electrochemical surface area of 60.24 mF/cm〈sup〉2〈/sup〉 in 0.5 M H〈sub〉2〈/sub〉SO〈sub〉4.〈/sub〉 The present work provides an intriguing strategy for developing trace loadings of noble metal electrocatalysts on inert materials with high HER performance.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314458-fx1.jpg" width="374" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Kiattisak Promsuwan, Napada Kachatong, Warakorn Limbut〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This work presents a novel flow injection-based non-enzymatic glucose sensor that uses an electrode modified with a nanocomposite of mullti-walled carbon nanotubes wrapped with palladium nanoparticle-graphene nanoplatelets (PdNPs-GNPs/MWCNTs). The nanocomposite was prepared using a reducing agent and ultra-sonication. A glassy carbon electrode (GCE) was modified by drop casting a suspension of the nanocomposites onto the electrode, which was dried in 5 min at 70 °C. The modified electrode exhibited strong catalytic activity for glucose oxidation at a low working potential (−0.10 V). The linear range of detection was wide (0.025–10 and 10–100 mM) and the system showed good sensitivity (83.0 and 52.9 μA mM〈sup〉−1〈/sup〉 cm〈sup〉−2〈/sup〉) with a low limit of detection (0.008 mM). Repeatability (RSD 〈 4.7%, n = 20), reproducibility (RSD = 1.4%, n = 6) and operational stability (116 injections per electrode, RSD = 3%) were good at high sample throughputs (60 samples hour〈sup〉−1〈/sup〉). Selective response to glucose was excellent in the presence of physiological levels of interferences commonly found in human blood. Glucose was detected with an RSD below 4% and recovery between 97 ± 4% and 99 ± 4%: comparable results to those obtained from standard hexokinase-spectrophotometric detection. The analytical performance of the sensor was suitable for routine analysis of glucose and other analytes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314690-egi10CX33KLPP3.jpg" width="399" alt="Image 10333" title="Image 10333"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Pengcheng Du, Yuman Dong, Hongxing Kang, Qi Wang, Jingye Niu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉p-Phenylene diamine (PPD) was selected as functional monomer to modify the holey graphene networks (rHGO-PPD) by a facile one-step hydrothermal method. rHGO-PPD was employed as promising active electrode materials to apply in supercapacitors (SCs), which exhibited excellent electrochemical performance, including high specific capacitance (375.5 F/g at current density of 0.5 A/g), excellent rate capability and good cycling stability due to the contribute of pseudocapacitive behavior of PPD. For further pursuit of great value in the practical application, the rHGO-PPD was used to fabricate symmetric SCs and flexible solid-state SCs (FSSCs). The FSSCs possessed high specific capacitance of 332.4 F/g, maintained good cycling stability of 74% of its initial capacitance up to 5000 charge-discharge cycles. In addition, FSSCs also exhibited extraordinary mechanical flexibility, and also maintained excellent stability even in a harsh environment. Remarkably, the FSSCs showed excellent long-term storage stability, and the capacitance kept about 88% after ten weeks of storage. Therefore, the FSSCs based on rHGO-PPD electrode material display promising application in 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-S0013468619314586-fx1.jpg" width="255" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Fabian Jeschull, Yuri Surace, Simone Zürcher, Michael E. Spahr, Petr Novák, Sigita Trabesinger〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, the use of silicon as a capacity-enhancing electrode additive to graphite electrodes was investigated. Based on energy-density estimations, the silicon amount was restricted to less than 20 wt%. The viability of such graphite–Si electrode blends was evaluated with regard to their cycle-life in relation to the silicon content of the electrode, showing how Si content and capacity fade are correlated. The addition of Si gradually alters the electrode morphology as shown by electrode cross-section images, and is partly responsible for the progressive capacity loss. In addition, we also demonstrate how analysis of the voltage hysteresis can provide early indications of cell failure. To complete the picture, one graphite–Si formulation was evaluated in a full-cell setup. The electrochemical study of this 3-electrode setup is complemented by a charge-injection experiment that replenishes the Li inventory and serves to pinpoint the origins of capacity fading more accurately under the cycling conditions chosen.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314501-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Andrés López‒Coronel, Euth Ortiz‒Ortega, Luis J. Torres‒Pacheco, Minerva Guerra‒Balcázar, Luis Gerardo Arriaga, Lorena Álvarez‒Contreras, Noé Arjona〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The development of bimetallic nanomaterials with well‒defined facets is highly desired in electrocatalysis to improve the alcohols oxidation. In this work, PdAg nanoparticles containing abundance of (100) facets and Pd nanocubes enclosed within (100) facets as control are synthesized and used as electrocatalysts towards ethylene glycol oxidation in alkaline medium. Transmission electron microscopy (TEM) and high‒resolution transmission electron microscopy (HR‒TEM) reveal that PdAg is composed by semispherical and semi‒cubic nanoparticles with average sizes of 4.1 ± 0.45 nm; Pd shows a well‒defined nanocubes shape with particles sizes of 9.9 ± 0.53 nm. X‒ray diffraction and X‒ray photoelectron spectroscopy (XPS) confirm the presence of Pd〈sup〉0〈/sup〉 in the PdAg material. Elemental mapping analysis of PdAg/C material at different electrochemical cycles indicates that PdAg has an atomic composition of Pd〈sub〉30〈/sub〉Ag〈sub〉70〈/sub〉, and it is maintained during the electrochemical experiments. The presence of (100) facets and silver in the PdAg electrocatalyst improves the EGOR activity; decreasing the onset potential and improving current density and stability. Microfluidic fuel cell evaluation shows higher cell voltage (0.71 V) for PdAg in comparison to Pd nanocubes (0.51 V), presenting similar power densities (5.2 mW cm〈sup〉−2〈/sup〉) despite PdAg uses 2.6 lower Pd loading, and it has high stability in a pH‒dual electrolyte configuration.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉PdAg with abundance of (100) facets containing semi-cubic shapes displayed high stability and similar performance than Pd nanocubes using 2.6 lower Pd loading.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314707-fx1.jpg" width="440" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Jing Hao, Guofeng Zhang, Yiteng Zheng, Wenhao Luo, Cen Jin, Ran Wang, Zhen Wang, Wenjun Zheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ni〈sub〉3〈/sub〉C is very promising in electrocatalytic field. However, it is rarely reported due to its harsh synthesis conditions. Herein, pure metallic Ni〈sub〉3〈/sub〉C nanoparticles in situ embedded in two-dimensional (2D) nitrogen-doped carbon nanoflakes (Ni〈sub〉3〈/sub〉C/NC nanoflakes) are successfully prepared through one-step pyrolyzing Ni-urea complex at a relatively mild temperature at 350 °C. The composition and nanostructure of the catalyst can be easily controlled by adjusting the synthetic conditions, such as pyrolysis temperature and reactant concentration. The NC nanoflakes with a large specific surface area and massive mesopores present a 2D morphology, which is beneficial to disperse Ni〈sub〉3〈/sub〉C nanoparticles to maintain their high conductivity. Based on advantage of nanostructure, Ni〈sub〉3〈/sub〉C/NC nanoflakes exhibit high electrocatalytic performance with a low overpotential of 309 mV, small Tafel slope of 72 mV dec〈sup〉−1〈/sup〉, as well as good stability. Furthermore, this study could provide a new strategy for the design and fabrication of other transition-metal carbides.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Md Azimur Rahman, Felipe Mojica, Mrittunjoy Sarker, Po-Ya Abel Chuang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The limiting current method is an effective in-situ diagnostic tool for studying oxygen transport resistance in a PEM fuel cell. In this study, we present both experimental and modeling results of a PEMFC operating from open circuit voltage to limiting current conditions. Operating conditions are 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈msup〉〈mrow〉〈mn〉80〈/mn〉〈/mrow〉〈mrow〉〈mo〉∘〈/mo〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉 C and 64% relative humidity. Pressure is varied from 118 kPa, 151 kPa, 201 kPa and 301 kPa. For each pressure the dry oxygen mole fraction is also varied from 1%, 2%, 3% and 4%. The ratio of porosity to tortuosity and the pressure independent 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi〉O〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 transport resistance used in the newly developed 1-D steady state model are obtained from the in-situ limiting current experiment. The model incorporates non-isothermal heat transfer, convective and diffusive gas transport, electrochemical reaction kinetics, shorting and hydrogen cross over current, effects of land and channel geometry on transport resistance, membrane water balance and proton resistance based on non-linear water content in the membrane. The simulation results are validated by polarization curves and limiting current tests at various operation conditions. This steady state 1-D dry model successfully integrate and implement interactive multiphysics to predict fuel cell performance under dry operating conditions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Hyun-joo Yang, Harim Kwon, Byung-Kwon Kim, Jun Hui Park〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report the electrochemical detection of single water droplets in an electrolyte-free organic solvent by collision events using a platinum ultramicroelectrode (Pt-UME). Water droplet emulsions were prepared by the ultrasonication of an organic solvent (e.g., dichloroethane) and an aqueous solution containing hydroquinone (H〈sub〉2〈/sub〉Q) as the redox species and MgSO〈sub〉4〈/sub〉 as an emulsion stabilizer as well as the supporting electrolyte. Under the appropriate potentials, we could observe single water droplet collision phenomena at the Pt-UME by amperometric current-time (〈em〉I-t〈/em〉) measurements. Water droplets that established contact with the Pt-UME led to amperometric current spikes due to the instantaneous electrolysis of the constituent redox species. The concentration of H〈sub〉2〈/sub〉Q in the emulsion was adjusted to confirm that the amperometric spike resulted from the electrochemical reaction in the water droplet. As the concentration of H〈sub〉2〈/sub〉Q increased, the oxidation peak current increased. The size and contact area of the water droplets were also estimated. Based on these single droplet collision results, we could successfully establish a facile water droplet detection system in an organic solvent without the addition of a hydrophobic organic electrolyte.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314689-fx1.jpg" width="489" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Martina Fracchia, Vito Cristino, Alberto Vertova, Sandra Rondinini, Stefano Caramori, Paolo Ghigna, Alessandro Minguzzi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉In this work we demonstrate the feasibility of hard X-rays operando XAS in photoelectrochemistry. WO〈sub〉3〈/sub〉, one of the most studied photoanodes for water splitting and for environmental remediation, is here studied at the W L〈sub〉III〈/sub〉-edge. This guarantees the direct observation of the W 5〈em〉d〈/em〉 band.〈/p〉 〈p〉The material, that is preliminary fully characterized in terms of its photoelectrochemical features, is studied in a three-electrode spectroelectrochemical cell, while X-ray absorption is measured in the X-ray absorption near edge structure (XANES) region.〈/p〉 〈p〉The recording of differential spectra and the monitoring of X-ray absorption at constant energy are used to compensate for the little XANES differences expected in the dark and under visible light illumination, which otherwise risks to be masked by experimental errors and/or by signal manipulation for data analysis.〈/p〉 〈p〉The results point to the filling of the W 〈em〉t〈/em〉〈sub〉〈em〉2g〈/em〉〈/sub〉 orbitals under illumination, that is followed by a structural rearrangement that compensates for the accumulation of electrons in the conduction band under open circuit (OC) conditions.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Ziyan Zhu, Linda Wu, James J. Noël, David W. Shoesmith〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The anodic behaviour of simulated spent nuclear fuel (SIMFUEL) was studied in NaCl solutions containing H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 and various concentration of HCO〈sub〉3〈/sub〉〈sup〉−〈/sup〉/CO〈sub〉3〈/sub〉〈sup〉2−〈/sup〉 using electrochemical, surface and solution analytical techniques. The two main anodic reactions are the oxidative dissolution of UO〈sub〉2〈/sub〉 and H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 oxidation. The relative importance of both reactions is controlled by the presence or absence of noble metal (〈em〉ε〈/em〉) particles dispersed throughout the UO〈sub〉2〈/sub〉 matrix, the applied potential and the HCO〈sub〉3〈/sub〉〈sup〉−〈/sup〉/CO〈sub〉3〈/sub〉〈sup〉2−〈/sup〉 concentration. Both reactions are suppressed by the formation of U〈sup〉VI〈/sup〉 surface films. When the formation of these films is prevented at higher HCO〈sub〉3〈/sub〉〈sup〉−〈/sup〉/CO〈sub〉3〈/sub〉〈sup〉2−〈/sup〉 concentrations, both reactions occur readily on the sublayer of U〈sup〉IV〈/sup〉〈sub〉1-2x〈/sub〉U〈sup〉V〈/sup〉〈sub〉2x〈/sub〉O〈sub〉2+x〈/sub〉. When present, noble metal (〈em〉ε〈/em〉) particles support H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 oxidation over the full potential range. At low potentials the peroxycarbonate (HCO〈sub〉4〈/sub〉〈sup〉−〈/sup〉) species formed is rapidly oxidized on the particles. At high potentials H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 can be directly oxidized on the noble metal particles rendered catalytic by pre-oxidation (e.g., Pd to Pd〈sup〉II〈/sup〉).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Fengjian Lin, Ming Yuan, Yuan Chen, Yunpeng Huang, Jiabiao Lian, Jingxia Qiu, Hui Xu, Huaming Li, Shouqi Yuan, Yan Zhao, Shunsheng Cao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Unique molybdenum trioxide decorated nickel-cobalt oxide nanostructures (MoO〈sub〉3〈/sub〉/NiCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉-NSs) and three-dimensional hierarchical structure α-FeOOH/rGO film were prepared via facile hydrothermal and annealing strategies. Owing to the merits of the large surface area, superior ionic conductivity, increased availability of active sites/interfaces, rich mixed valences of polymetallic oxide and the favorable structural stability, the as-prepared optimized battery-type MoO〈sub〉3〈/sub〉/NiCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉-NSs electrode material presents an extraordinary specific capacity (1042 F g〈sup〉−1〈/sup〉 at 1 A g〈sup〉−1〈/sup〉), largely improved rate capability (93%, from 1 to 6 A g〈sup〉−1〈/sup〉), and superior cycling performance, compared with the NiCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉–NCs, MoO〈sub〉3〈/sub〉, and also exceeds some of the reported Ni-, Co-based electrodes. Underlying such great improvement, a MoO〈sub〉3〈/sub〉/NiCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉-NSs//α-FeOOH/rGO asymmetric supercapacitor device with a large potential window was assembled, which delivered a high capacitance of 141 F g〈sup〉−1〈/sup〉 at 1 A g〈sup〉−1〈/sup〉, an excellent energy density of 50.2 Wh kg〈sup〉−1〈/sup〉, and an amazing power density of 4.8 kW kg〈sup〉−1〈/sup〉. The serially connected asymmetric supercapacitor can power commercial light-emitting diodes suggesting their potential application for electronic gadgets. The superior energy storage characteristics of the asymmetric supercapacitor are strongly attributed to the interconnected 3D nanoporous network architectures of the MoO〈sub〉3〈/sub〉/NiCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉-NSs and the good compatibility with the α-FeOOH/rGO negative electrode.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Unique MoO〈sub〉3〈/sub〉/NiCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉-NSs and α-FeOOH/rGO film were successfully synthesized for supercapacitor applications. The optimized MoO〈sub〉3〈/sub〉/NiCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉-NSs electrode presents a high specific capacity (1042 F/g at 1 A/g), improved rate performance (93%, from 1 A/g to 6 A/g), and superior cycling performance (110% capacitance retention after 2000 cycles). A MoO〈sub〉3〈/sub〉/NiCo〈sub〉2〈/sub〉O〈sub〉4〈/sub〉-NSs//α-FeOOH/rGO asymmetric supercapacitor delivered an excellent energy density (50.2 Wh kg〈sup〉−1〈/sup〉) and an amazing power density (4.8 kW kg〈sup〉−1〈/sup〉).〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314288-fx1.jpg" width="395" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Qingfeng Zhou, Yun Gong, Keyu Tao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Binary metal compounds have higher conductivity and richer redox reactions due to the co-existence and synergism of different transition metals. Besides, carbon in composite materials has the advantage of enhancing electronic conductivity to promote fast electron transmission. Herein, a series of Ni〈sub〉m〈/sub〉P〈sub〉n〈/sub〉/C, Ni〈sub〉2〈/sub〉P/C, Co〈sub〉2〈/sub〉P/C and Ni〈sub〉x〈/sub〉Co〈sub〉2-x〈/sub〉P/C nanohybrids with different Ni/Co molar ratios were synthesized by in-situ calcination/phosphorization of MOF precursors. These nanohybrid materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive spectrometer and electrochemical tests. The NiCoP/C material possesses a granular structure with NiCoP nanoparticles anchored in a large number of carbon. Taking advantage of the bimetallic synergism and carbon anchoring effect, the as-prepared NiCoP/C sample delivers the most prominent specific capacities of 775.7C g〈sup〉−1〈/sup〉 at 1 A g〈sup〉−1〈/sup〉, and 582.4C g〈sup〉−1〈/sup〉 at 20 A g〈sup〉−1〈/sup〉 (20-fold) with a superior rate capability of 75.1% retention, much superior to those of the corresponding Ni〈sub〉m〈/sub〉P〈sub〉n〈/sub〉/C, Ni〈sub〉2〈/sub〉P/C, Co〈sub〉2〈/sub〉P/C, other Ni〈sub〉x〈/sub〉Co〈sub〉2-x〈/sub〉P/C samples and various reported metal phosphide nanostructures/nanocomposites. Furthermore, the constructed NiCoP/C//activated carbon asymmetric supercapacitor can exhibit a high energy density of 47.6 Wh kg〈sup〉−1〈/sup〉 at a power density of 798.9 W kg〈sup〉−1〈/sup〉, which was superior to those previously reported of Ni/Co phosphide nanomaterials.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314306-fx1.jpg" width="370" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 10 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 320〈/p〉 〈p〉Author(s): Irene Reche, Silvia Mena, Iluminada Gallardo, Gonzalo Guirado〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This manuscript presents an efficient approach for producing high valuable compounds using CO〈sub〉2〈/sub〉 as building block. The methodology employed is based on electrochemical techniques, which allow performing eco-friendly chemistry solutions and maintaining the aim of offering a potential long-term strategy for reducing the CO〈sub〉2〈/sub〉 emissions in the atmosphere, while obtaining useful compounds, such as aromatic acids and phthalate derivatives. This work describes the electrochemical reduction behavior of 4-halobenzonitrile compounds using Glassy Carbon and Silver as cathodes under inert and carbon dioxide atmosphere. Controlled potential electrolysis of 4-halobenzonitriles under CO〈sub〉2〈/sub〉 allows obtaining, in very good yields, the corresponding mono- and di-carboxylated organic compounds in CO〈sub〉2〈/sub〉-saturated solutions of dimethylformamide containing 0.1 M of tetrabutylammonium tetrafluoroborate. Electro-catalytic effects are seen when Ag is used a cathode, which give very high yields, especially as regards di-carboxylated products. The methodology offers a new “green” route for the synthesis of different phthalate derivatives, which can be potentially used for making plastic polymers in a more environmentally friendly way.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619314215-egi10SXT6PJW0X.jpg" width="500" alt="Image 1010" title="Image 1010"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Dong-Dong Ma, Changsheng Cao, Xiaofang Li, Jin-Tian Cheng, Li-Li Zhou, Xin-Tao Wu, Qi-Long Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The development of highly active and stable electrocatalysts for the oxygen evolution reaction is of great importance for renewable-energy. Herein, a novel hybrid nanomaterial with multicomponent active dopants was conveniently fabricated by pyrolytic conversion from a bimetallic ion-decorated heteroatom-rich (P, S and N) covalent organic polymer (COP) composite. The unique nanostructure with innumerable Co〈sub〉9-〈em〉x〈/em〉〈/sub〉Ni〈sub〉〈em〉x〈/em〉〈/sub〉S〈sub〉8〈/sub〉 and CoNiP nanoparticles anchored on P/S/N multi-doped carbon/carbon nanotubes, through in situ electrochemical reconstruction effectively provides substantial active sites and promotes charge transfer, and hence affords outstanding activity with a low overpotential of 270 mV at 10 mA cm〈sup〉−2〈/sup〉 and excellent stability for oxygen evolution reaction based on two runs of 10-h durability test in alkaline solution, which much outperformed the fewer-component counterparts.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619315506-fx1.jpg" width="296" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Yang Yang, Liang He, Jianfang Lu, Ziying Liu, Ningying Wang, Jing Su, Yunfei Long, Xiaoyan Lv, Yanxuan Wen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Manganese oxalate is a novel conversion anode material for lithium ion batteries, but its low conductivity limits its application. To overcome this drawback, we report MnC〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 microtubes prepared 〈em〉via〈/em〉 a rapid assembly process in a T-type microchannel reactor. The X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) images confirm that MnC〈sub〉2〈/sub〉O〈sub〉4〈/sub〉·2H〈sub〉2〈/sub〉O microtubes are monoclinic α phase with a C2/c space group; MnC〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 microtubes have a 〈em〉Pmna〈/em〉 orthorhombic structure. As-synthesized MnC〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 microtubes exhibit a high reversible capacity of 925 mAh⋅g〈sup〉−1〈/sup〉 after 100 cycles at 1 A ⋅g〈sup〉−1〈/sup〉. Even at an ultra-high current density of 5 A⋅ g〈sup〉−1〈/sup〉, the anode MnC〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 microtubes deliver a constant discharge capacity of 721 mAh⋅g〈sup〉−1〈/sup〉 with a capacity retention of 97% on the 100th cycle. The improved performance can be attributed to the unique microtube structure composed of MnC〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 nanoparticles, leading to faster electrode kinetics.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Qiujun Li, Hua Yao, Feng Liu, Zitao Gao, Yangyi Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A new Mn-doped coordination supramolecular network (CSN) was synthesized on nickel foam directly by a simple one-step hydrothermal method. Compared with the pure CSN electrode (∼2.46 C cm〈sup〉−2〈/sup〉 at 10 mA cm〈sup〉−2〈/sup〉), this Mn-doped binder-free electrode showed an ultrahigh areal capacity (∼8.12 C cm〈sup〉−2〈/sup〉 at 10 mA cm〈sup〉−2〈/sup〉). In addition, when the current density increased from 10 mA cm〈sup〉−2〈/sup〉 to 50 mA cm〈sup〉−2〈/sup〉, it had a good rate capability with 73.33% capacitance retention. For practicality, an asymmetrical supercapacitor (ASC) was assembled by Activated Carbon (AC) electrode and the Mn-doped CSN electrode. The device not only could achieve a maximum energy density of 3.41 mW h cm〈sup〉−3〈/sup〉 at the power density of 44.98 mW cm〈sup〉−3〈/sup〉, but also could exhibit excellent stability after 4000 cycles, with the capacitance retention of 90.14%. The above results indicate that the Mn-doped CSNs are promising electrode materials for supercapacitors in energy storage.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Lingbo Ren, Jian-Gan Wang, Huanyan Liu, Minhua Shao, Bingqing Wei〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Prussian blue and its analogues are recognized as a class of attractive materials for stationary energy storage on the electrical grid. Challenges are still existed to meet the rigid requirements of high power and long cycle life. In this work, we develop a universal metal-organic-framework templating strategy for fabricating hollow polyhedrons of prussian blue analogues with tailored composition and shape. Hollow dodecahedrons of cobalt hexacyanoferrate (CoHCF) are investigated as a proof-of-concept material, which shows high surface area and mesoporous characteristics. The CoHCF hollow dodecahedrons exhibit large Na + storage capacity in neutral aqueous electrolytes and particularly, superhigh rate capability owing to rapid ion diffusion rate and short carrier transport distances. By coupling with a low-cost carbon anode, hybrid Na-ion cells are constructed to deliver moderate specific energy (32.7–50 Wh kg〈sup〉−1〈/sup〉), a high specific power of 30 kW kg〈sup〉−1〈/sup〉, and superior 3000-cycling durability. The excellent electrochemical properties make the present aqueous Na-ion hybrid devices to be a promising alternative to lead-acid batteries for high power grid-scale energy storage.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Chen Li, Yong Xiang, Wenguan Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present study, the effect of an SO〈sub〉2〈/sub〉 impurity on the electrochemical behaviour of X80 steel in CO〈sub〉2〈/sub〉-saturated solution was evaluated within a carbon capture, utilization and storage system. In the initial stage of corrosion, although SO〈sub〉2〈/sub〉 dissolved in water reduced the pH of the solution, the inhibition of corrosion by SO〈sub〉2〈/sub〉 and its hydrolysate adsorbed on the surface of X80 steel dominated the corrosion behaviour. Under anaerobic conditions, SO〈sub〉2〈/sub〉 was converted to S〈sup〉−〈/sup〉 and S〈sup〉2−〈/sup〉, which reduced the adsorbed SO〈sub〉2〈/sub〉 molecules. The FeS and FeS〈sub〉2〈/sub〉 corrosion product scales which took shape on the surface of X80 steel had poor adhesion and could only provide limited protection. However, the corrosion product scale occupied the adsorption region of SO〈sub〉2〈/sub〉 and its hydrolysate, resulting in an increase in the corrosion rate. The adsorption of SO〈sub〉2〈/sub〉 molecule and the hydrolysate and the protective properties of the corrosion product scale affect the corrosion mechanism of X80 in CO〈sub〉2〈/sub〉/SO〈sub〉2〈/sub〉-saturated solution.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619315312-egi10FF52WR4S4.jpg" width="500" alt="Image 105244" title="Image 105244"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Hui-Liang Chang, Yi-Wen Bai, Xiao-Yi Song, Yan-Fang Duan, Ping-Ping Sun, Bo Tian, Guimei Shi, Hongpeng You, Jun Gao, Fa-Nian Shi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Three phosphonates coordination polymers containing different metal ions with the molecular formula C〈sub〉15〈/sub〉H〈sub〉32〈/sub〉N〈sub〉3〈/sub〉M〈sub〉2〈/sub〉O〈sub〉16〈/sub〉P [M = Ni (PN1) and Co (PC1)] and C〈sub〉30〈/sub〉H〈sub〉50〈/sub〉N〈sub〉6〈/sub〉Ni〈sub〉2.67〈/sub〉Co〈sub〉1.33〈/sub〉O〈sub〉27〈/sub〉P〈sub〉2〈/sub〉 (PNC) were prepared by mild hydrothermal synthesis at 100 °C for 48 h. All 3 phosphonates are composed of two different ligands: N-(phosphonomethyl)iminodiacetate (pmida) and 4,4′-bipyridine (4,4′-bpy). The structures of the materials were elucidated via single crystal X-ray diffraction techniques which show all compounds have the similar hybrid three dimensional (3-D) super structures via hydrogen bonds in triclinic symmetric and 〈em〉P-1〈/em〉 space group. The morphologies of the particles were characterized by SEM showing the irregular block shape. The electrochemical properties of 3 phosphonates were studied by cyclic voltammetry (CV), alternating current impedance spectroscopy (EIS) and constant current charge-discharge measurements. The discharge capacity remains to 288.1 mAh/g at 100〈sup〉th〈/sup〉 cycle with a current density of 50 mA/g and still behaves a growing trend. The CV data shows the large range of 0–10 V with the reduction peak at 4.7 V suggest that PC1 may be suitable for preparing high voltage lithium ion batteries (Libs). The performance of PC1 indicate promising for potential negative electrode material for Libs.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Shujie Dai, Yong Feng, Peng Wang, Hui Wang, Huagen Liang, Rongfang Wang, Vladimir Linkov, Shan Ji〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Due to their high energy density, lithium-sulfur (Li/S) batteries are among the most promising future power sources to replace modern lithium ion batteries, but low conductivity of sulfur-based cathodes significantly impedes their practical applications. In this study, novel conductive sulfur-rich copolymer/sulfur cathode materials, cp(S-〈em〉g〈/em〉-PANI)/S (SPAS), are developed by grafting conductive polymer segments onto copolymer backbones to improve cell electrical conductivity and enhance lithium diffusion. In a Li/S cell, newly obtained composites deliver an initial discharge capacity of 1151 mAh g〈sub〉sulfur〈/sub〉〈sup〉−1〈/sup〉 at a current density of 0.1C. Compared to composites lacking conductive polymer segments in the copolymer backbone, such as cp(S-AS)/S (SAS), SPAS provide better rate performance when current density is increased from 0.1C to 5C and exhibit good cycling stability at 0.5C. High capacity and cycling stability of SPAS as lithium-sulfur battery cathodes are ascribed to a synergetic effect between sufur-rich copolymer and conductive PANI.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 20 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Electrochimica Acta, Volume 321〈/p〉 〈p〉Author(s): Shih-Ching Huang, Chia-Yu Lin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present the anodic pulse-current electrosynthesis, structural characterization, and OER electrocatalytic properties of the pristine and anodically-pretreated nickel-iron oxyhydroxide borate thin films (Fe:Ni–Bi). In the electrosynthesis of Fe:Ni–Bi, OER kinetics was found to have great influence not only on the current efficiency for film deposition, but also on the surface morphology and crystal structure of the synthesized Fe:Ni–Bi. In addition, the Tafel analyses indicate that incorporating iron modified the OER mechanism and promoted the OER activity. Moreover, both the applied turnover (current) and electrolyte pH used in the anodic pretreatment of Fe:Ni–Bi have great influences on the OER activity of the pretreated Fe:Ni–Bi; the applied turnover rate decides the applied oxidative level and thus affects the extent of phase transformation of β-NiOOH to γ-NiOOH, whereas the solution pH for anodic pretreatment affects the electrochemically effective surface area. Finally, the developed electrosynthetic approach can effectively translate the high OER activity of Fe:Ni–Bi from a flat FTO substrate to a porous BiVO〈sub〉4〈/sub〉 photoanode, facilitating the interfacial hole transfer and improving photostability of BiVO〈sub〉4〈/sub〉.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉The main factors in determining the OER activity of Fe:Ni–Bi, prepared by anodic pulse electrodeposition, are elucidated in this work, including (i) Fe incorporation to modify OER mechanism, (ii) applied turnover frequency to affect the extent of phase transition to OER active γ-NiOOH, and (iii) pretreatment in alkaline electrolyte to enlarge the electrochemically effective surface area.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0013468619315385-fx1.jpg" width="313" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉