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〉