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  • 1
    Publication Date: 2018-07-05
    Description: Publication date: 1 September 2018 Source: Electrochimica Acta, Volume 283 Author(s): M. Celina Bonetto, Fernando F. Muñoz, Virginia E. Diz, Natalia J. Sacco, Eduardo Cortón Glassy carbon electrodes (GC) were modified with multiwalled carbon nanotubes (MWCNT/GC) and electrochemically treated first by applying an oxidation potential and then a reduction potential. The resulting electrodes were characterized via scanning electron microscopy, Raman spectroscopy, energy dispersive spectroscopy, and electrochemical techniques, particularly cyclic voltammetry using the redox probes Fe(CN) 6 3− /4- and Ru(NH 3 ) 2+/3+ and electrochemical impedance spectroscopy using Fe(CN) 6 3− /4- . These modified electrodes showed an electrochemical determination selective for dopamine (DA) and serotonin (5HT) in the presence of ascorbic acid (AA) and uric acid (UA), simultaneously measured, with a high reproducibility (an RSD of 1.7% for DA and 1.6% for 5HT) and a limit of detection (LOD) of 235 nmol L −1 for DA and 460 nmol L −1 for 5HT. The GC electrodes modified with oxidized MWCNT, subsequently reduced, showed higher selectivity towards the oxidation of DA and 5HT compared with GC bare electrodes or modified with MWCNT or oxidized MWCNT. Graphical abstract
    Print ISSN: 0013-4686
    Electronic ISSN: 1873-3859
    Topics: Chemistry and Pharmacology , Physics
    Published by Elsevier
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  • 2
    Publication Date: 2018-07-05
    Description: Publication date: 1 September 2018 Source: Electrochimica Acta, Volume 283 Author(s): Jia-hua Liu, Xiao-ying Xu, Weibang Lu, Xinbo Xiong, Xing Ouyang, Changhui Zhao, Fei Wang, Si-yin Qin, Jiao-ling Hong, Jiao-ning Tang, Da-Zhu Chen A new type of ternary carbon nanotube fiber (CNF)/three-dimensional (3D) porous carbon nanotubes (CNTs)/polyaniline (PANI) electrodes with a double core-sheathed architecture composed of CNF/CNTs and CNTs/PANI was fabricated via low-potential electrophoretic deposition of CNTs and subsequent electrochemical polymerization of PANI on the CNF surface. The resulting all-solid-state supercapacitor possesses a high specific capacitance of 67.31 mF cm −2 at the current density of 0.5 mA cm −2 and only a loss as less as 10% of its initial specific capacitance after 5000 charge-discharge cycles. Furthermore, it is capable of withstanding different bending deformations, and can maintain 99.8% capacitance, even after experiencing the bending of 180° for 500 times, which manifests a significant application potential in the field of flexible electronic devices. Graphical abstract
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    Electronic ISSN: 1873-3859
    Topics: Chemistry and Pharmacology , Physics
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  • 3
    Publication Date: 2018-07-05
    Description: Publication date: 1 September 2018 Source: Electrochimica Acta, Volume 283 Author(s): Chang-sheng An, Bao Zhang, Lin-bo Tang, Bin Xiao, Jun-chao Zheng LiFePO 4 is one of the most promising cathode materials for Li-ion batteries. However, its low electronic conductivity and slow Li-ion diffusion rate lead to poor electrochemical performance, especially poor rate performance. The hybrid of LiFePO 4 /Nitrogen and Sulfur co-doped graphene is successfully synthesized via a self-assembly method. Given its Nitrogen and Sulfur co-doped graphene matrix, the hybrid exerts a significantly impact on the electron conductivity of LiFePO 4 , resulting in excellent electrochemical properties and power density. The LiFePO 4 composite has reversible capacity of 106.1 mAhg −1  at 10 C and 94.6 mAhg −1 at 15 C. Moreover, with less than 5% loss of discharge capacity after 500 cycles at 10 C, the Nitrogen and Sulfur co-doped graphene can effectively improve the electrochemical performance of LiFePO 4 .
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    Electronic ISSN: 1873-3859
    Topics: Chemistry and Pharmacology , Physics
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  • 4
    Publication Date: 2018-07-05
    Description: Publication date: 1 September 2018 Source: Electrochimica Acta, Volume 283 Author(s): Amol Bhairuba Ikhe, Nirmalesh Naveen, Kee-Sun Sohn, Myoungho Pyo Poly(hexyl viologen dichloride) (PHV-Cl) is described as a high energy density (ED) material in magnesium-based electrolytes. When coupled with Mg metal in all phenyl complex (APC) electrolytes, PHV-Cl cathodes demonstrate anion-transport behaviors with the reduction/oxidation of viologen units. This dual-ion type cell delivers a relatively high ED with reasonable stability during repeated charge/discharge (C/D) when compared with previously reported inorganic/organic cathodes in magnesium-ion batteries (MIBs). PHV-Cl shows a capacity of 171 mAh g −1 at an average discharge potential of 1.33 V vs. Mg/Mg 2+ , resulting in a significantly high ED (227 mWh g −1 ). The high ED characteristics of PHV-Cl are retained during repeated C/D cycles (201 mWh g −1 after 50 C/D) in contrast to the relative instability of other previously reported organic cathodes. Herein, the electrochemical performance of PHV-Cl in various types of electrolytes is also described. This work suggests that viologen-based cathodes with anion-transport properties could be implemented to achieve high levels of ED and stability via a dual-ion mode in MIBs, particularly with currently available electrolytes that are compatible with magnesium metal. Graphical abstract
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    Electronic ISSN: 1873-3859
    Topics: Chemistry and Pharmacology , Physics
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  • 5
    Publication Date: 2018-07-05
    Description: Publication date: 1 September 2018 Source: Electrochimica Acta, Volume 283 Author(s): Muhammad Imtiaz, Zhixin Chen, Chengling Zhu, Hui Pan, Imran Zada, Yao Li, Syeda Wishal Bokhari, RuiYing Luan, Salma Nigar, Shenmin Zhu Sugarcane bagasse, a waste product of the sugarcane industry can be used as a precursor for the preparation of carbon. In this study, a composite consisting of hierarchically functionalized porous carbon (FPC) and β-FeOOH was synthesized via a simple and effective hydrolysis method. The hydrothermal process before the carbonization and activation of the bagasse maintained the hierarchical interconnected porous structure of the sugarcane bagasse. A nitric acid (HNO 3 ) functionalization treatment enabled an in-situ growth of β-FeOOH on the hierarchically structured bagasse. When tested as an anode for lithium-ion batteries, the obtained FPC/β-FeOOH composite showed a high discharge capacity of 898.8 mAh g −1 at 0.2 A g −1 after 350 cycles and achieved a specific capacity of 446.1 mAh g −1 at a current rate of 1 A g −1 after 1000 cycles together with a remarkable coulombic efficiency of 99.9%. This excellent electrochemical performance of the FPC/β-FeOOH composite can be attributed to the synergistic effect of the interconnected porous structure of porous carbon and the electrochemically active tunnel type β-FeOOH nanorods. The strategy developed here is promising in design and fabrication of other composites having interconnected porous structures with high performance. Graphical abstract
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    Electronic ISSN: 1873-3859
    Topics: Chemistry and Pharmacology , Physics
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  • 6
    Publication Date: 2018-07-04
    Description: Publication date: 1 September 2018 Source: Electrochimica Acta, Volume 283 Author(s): Dieter Britz, Jörg Strutwolf The two-dimensional Saul'yev method of simulating processes at a disk electrode is tested in the presence of homogeneous chemical reactions. The catalytic EC′ reaction can produce a thin reaction layer, which is a test of any simulation method. The second-order Birk/Perone (B/P) reaction is similarly a test because of the nonlinear term appearing in the kinetic equations (although it does not give rise to a thin reaction layer). The Saul'yev method handles these with no special problems and is competitive, in terms of speed, with implicit methods at similar accuracy (and faster in the case of the nonlinear B/P case).
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    Electronic ISSN: 1873-3859
    Topics: Chemistry and Pharmacology , Physics
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  • 7
    Publication Date: 2018-07-04
    Description: Publication date: 1 September 2018 Source: Electrochimica Acta, Volume 283 Author(s): Binhong He, Liang Chen, Mingjun Jing, Minjie Zhou, Zhaohui Hou, Xiaobo Chen Hydrogen evolution reaction (HER) through electrocatalytic water splitting is regarded as a promising route to produce hydrogen in a large scale. Molybdenum disulfide (MoS 2 ) has been reported as a transition metal electrocatalysts, but generally with a poor activity, e.g. 540 mV overpotential at 10 mA cm −2 and Tafel slope value of 84 mV dec −1 . A 3D MoS 2 -rGO@Mo nanohybrids, a three-dimensional MoS 2 nanosheets network coated with reduced graphene oxide (rGO) on molybdenum mesh, is demonstrated as one of the best MoS 2 -based electrocatalysts. It delivers a benchmark current density of 10 mA cm −2 under a small overpotential (∼123 mV) with a low Tafel slope (∼62 mV dec −1 ), and an excellent stability performance. Its excellent performance can be attributed to the synergy between the 3D MoS 2 and rGO with abundant active sites and high conductivity which leads to a faster water dissociation on the surface in the Volmer step. Graphical abstract
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    Electronic ISSN: 1873-3859
    Topics: Chemistry and Pharmacology , Physics
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  • 8
    Publication Date: 2018-07-04
    Description: Publication date: 1 September 2018 Source: Electrochimica Acta, Volume 283 Author(s): Rimpa Jaiswal, Uttam Saha, Thako Hari Goswami, Anurag Srivastava, N.Eswara Prasad The electrochemical performances of fullerenol functionalized graphene oxide (FGO) and reduced FGO (rFGO) were evaluated in acid, alkaline and neutral electrolytes at 5–200 mV/s scan rates in cyclic voltammetry (CV) and with galvanostatic charge/discharge (CD) up to 1000 cycles at 1 A/g current density. Typical nucleophilic addition reaction using hydroxyl functional groups of fullerenol [(Fol) n − anion as nucleophile] with epoxy & carboxyl groups of GO-acyl chloride in pyridine results the formation of FGO nanohybrid. Further reduction of FGO with hydrazine monohydrate in microwave synthesizer for 45 min at 80 °C would produce rFGO. XRD analyses of FGO and rFGO demonstrate edge to edge and basal to basal reactions between fullerenol and GO, whereas TEM images indicate the insertion of fullerene inside the graphene flakes. The redox reaction of residual basic electroactive oxygenated functional groups with protons able to produce an increasing trend in capacitance performance up to 300 cycles for rFGO (from 255 to 363 F/g at 1.0 A/g current density) in 1.0 M H 2 SO 4 electrolyte and can retains its highest capacitance value (368 F/g) even after 1000 cycles. Whereas, significantly lower capacitance values even in highly concentrated alkaline electrolytes (55.6 and 85.7 F/g at 5 mV/s scan rate in 1 & 6 M KOH for rFGO) reconfirm the GO-COOH participation towards the chemical reaction with fullerenol–OH groups. This capacitance value in acid electrolyte is much higher than those of the nanocomposites composed of cationic fullerene and anionic GO reported earlier. Consequently, rFGO reports higher energy density compared to rGO (51.11 vs 24.41 Wh/kg) in 1 M H 2 SO 4 and also shows about ten times higher power density (5018 vs 506.82 W/kg) in 1 M Na 2 SO 4 . Also, the electrochemical impedance analyses using Nyquist and Bode plots indicate more ideal supercapacitive characteristic for rFGO (77.8° vs 90°) and FGO (71.7° vs 90°) compared to rGO (21° vs 90°). Graphical abstract
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    Topics: Chemistry and Pharmacology , Physics
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  • 9
    Publication Date: 2018-07-04
    Description: Publication date: 1 September 2018 Source: Electrochimica Acta, Volume 283 Author(s): Muhammad Rashid, Asit Sahoo, Amit Gupta, Yogesh Sharma Lithium titanate oxide (Li 4 Ti 5 O 12 , LTO) is receiving significant attention as an alternative to graphitic anode due to high structural and thermal stability, and reduced possibility of formation of SEI film. In this study, Li 4 Ti 5 O 12 is synthesized by the solid-state method and its electrochemical characteristics are examined by cyclic voltammetry and galvanostatic charge-discharge techniques. Moreover, we demonstrate the first instance of a numerical model used to understand the role of cell parameters in Li-LTO half-cells. The simulated charge-discharge capacity curves at 0.5, 1.0 and 1.5 C currents are in good agreement with experimental findings. Using this model, the effect of particle size, lithium diffusivity and electrode thickness on the charge-discharge capacity of Li-LTO cells have been investigated. Simulations show that the cell capacity is highly dependent on lithium transport in the solid matrix specifically at high current. Critical analysis of lithium concentration inside the solid matrix reveals a poor utilization of lithium storage sites and lower cyclable lithium in case larger particles and lower lithium diffusivity. The rise in the thickness of electrode leads to the lower achievable specific capacity of the battery due to increased cell overpotential and transport limitations for Li-ions and electrons.
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  • 10
    Publication Date: 2018-07-04
    Description: Publication date: 1 September 2018 Source: Electrochimica Acta, Volume 283 Author(s): Chaoqun Niu, Mingke Zhang, Guangping Chen, Bokai Cao, Jiwei Shi, Jie Du, Yong Chen Polyacrylate polymer is a promising polymer matrix for gel polymer electrolyte (GPE) in lithium-ion batteries. Herein, in-situ polymerized poly(ethylene glycol phenyl etheracrylate) (PEGPEA) based GPE combined with 1 M LiPF6 in ethylene carbonate/dimethyl carbonate/ethyl methyl carbonate (EC/DMC/EMC, 1:1:1 in volume) solvents was introduced. The maximum recoverable strain of the in-situ polymerized PEGPEA-GPE was up to 99%. The outstanding interfacial compatibility between PEGPEA-GPE and the lithium electrode was also obtained. Surprisingly, lithium dendrite was effectively suppressed in charge-discharge cycling because of polymer-enhanced solid electrolyte interphase (SEI) and excellent contact interface. Furthermore, the PEGPEA-GPE exhibited wide electrochemical stability window up to 4.9 V versus Li + /Li, and achieved an ionic conductivity of 3.35 × 10 −3  S cm −1  at 25 °C. When used as electrolyte, the Li[Ni 0.5 Co 0.2 Mn 0.3 ]O 2 /PEGPEA-GPE/Li batteries showed high discharge capacity retention rate of 97.5% after 70 charge-discharge cycles and considerable discharge rate capability, i.e., 155 mAh g −1 0.2C, 142 mAh g −1 0.5C, 120 mAh g −1 1C, 60 mAh g −1 2C. These results demonstrate that this highly elastic in-situ polymerized PEGPEA-GPE is a potential electrolyte system for high-performance polymer electrolyte lithium-ion batteries and has excellent application prospects in wearable and flexible batteries.
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    Topics: Chemistry and Pharmacology , Physics
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