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Electrochemical Impedance of Ethanol Oxidation in Alkaline Media

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Chemical Research in Chinese Universities 2012年第1期28卷 19-25页

作者： DANAEE Iman JAFARIAN Majid gobal fereydoon SHARAFI Mahboobeh MAHJANI Mohammad-ghasem Abadan Faculty of Petroleum Engineering Petroleum University of Technology Abadan 63165-619 Iran Department of Chemistry K. N. Toosi University of Technology Tehran 15875-4416 Iran Department of Chemistry Sharif University of Technology Tehran 11365-9516 Iran

Nickel modified NiOOH electrodes were used for the electrocatalytic oxidation of ethanol in alkaline so lutions. The electro-oxidation of ethanol in a 1 mol/L NaOH solution at different concentrations of ethanol was stu died by ac impedance spectroscopy. Electrooxidation of ethanol on Ni shows negative resistance on impedance plots. The impedance shows different patterns at different applied anodic potential. The influence of the electrode potential on impedance was studied and a quantitative explanation for the impedance of ethanol oxidation was given by means of a proposed mathematical model. At potentials higher than 0.52 V（vs. Ag/AgCl）, a pseudoinductive behavior was observed, but at those higher than 0.57 V, impedance patterns were reversed to the second and third quadrants. The conditions required for the reversing of impedance pattern were delineated with the impedance model.

关键词： Impedance Equivalent circuit Ethanol Electrocatalytic Nickel

Synergistic effect of cobalt and copper on a nickel-based modified graphite electrode during methanol electro-oxidation in NaOH solution

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Chinese Journal of Catalysis 2015年第11期36卷 1867-1874页

作者： Tayebe Rostami Majid Jafarian Somaieh Miandari Mohammad G.Mahjani fereydoon gobal K.N.图什理工大学化学系谢里夫理工大学化学系

The electrocatalytic oxidation of methanol was studied over Ni, Co and Cu binary or ternary alloys on graphite electrodes in a NaOH solution （0.1 mol/L）. The catalysts were prepared by cycling the graphite electrode in solutions containing Ni, Cu and Co ions at cathodic potentials. The synergistic effects and catalytic activity of the modified electrodes were investigated by cyclic voltammetry （CV）, chronoamperometry CCA） and electrochemical impedance spectroscopy （EIS）. It was found that, in the presence of methanol, the modified Ni-based ternary alloy electrode （G/NiCuCo） exhibited a significantly higher response for methanol oxidation compared to the other samples. The anodic peak currents showed a linear dependency on the square root of the scan rate, which is a characteristic of a diffusion controlled process. During CA studies, the reaction exhibited Cottrellin behavior and the diffusion coefficient of methanol was determined to be 6.25× 10-6 cm2/s and the catalytic rate constant, K, for methanol oxidation was found to be 40×107 cm3/Cmol.s）. EIS was used to investigate the catalytic oxidation of methanol on the surface of the modified electrode.

关键词： Methanol electro-oxidation Electrocatalysis Synergistic effect Nickel Modified electrode

碱性介质中(氢)氧化铜修饰电极电催化氧化蔗糖(英文)

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催化学报 2010年第11期31卷 1351-1357页

作者： Majid JAFARIAN Mehdi RASHVAND AVEI Iman DANAEE fereydoon gobal Mohammad G.MAHJANI Department of Chemistry K.N.Toosi University of Technology Abadan Faculty of Petroleum Engineering Petroleum University of Technology Department of Chemistry Sharif University of Technology

A stable copper(hydr)oxide-modified electrode was prepared in 0.5 mol/L NaOH solution by cyclic voltammetry in the range of -250 to 1 000 *** can be used for electrochemical studies in the range of -250 to 1000 mV without interfering peaks because there is no oxidation of *** an anodic potential sweep,the electro-oxidation of saccharose on Cu occurred by the formation of CuⅢ and this reaction also occurred in the early stages of the reversed cycle until it is stopped by the negative potentials.A mechanism based on the electro-chemical generation of CuⅢ active sites and their subsequent consumption by saccharose was proposed,and the rate law and kinetic parameters were *** charge transfer resistance from theoretical and impedance studies was used to verify the *** chronoamperometry regimes,the reaction followed Cottrellian *** transfer of up to 21 electrons was observed in further investigations of the electro-oxidation of saccharose on a(hydr)oxide Cu rotating disk electrode.

关键词： saccharose copper(hydr)oxide equivalent circuit electrocatalytic oxidation mechanism