No abstract

Nickel-dimethylglyoxime complex (abbreviated as Ni(II)(DMG) 2 ) modified carbon paste and graphite electrodes were prepared by mixing Ni(II)(DMG) 2 with graphite paste, and coating Ni(II)(DMG) 2 to the graphite surface. It is necessary to cycle the electrode potential to a high value (e.g. 0.8 V versus SCE) for the preparation of the modified electrodes. The electrochemical reaction was originally assumed to be a one-electron process converting Ni(II)(DMG) 2 toNi(III)ONi(III)(OH)(DMG) 2 ] -showed a strong catalytic activity toward electro-oxidation of methanol and ethanol. The electrocatalytic oxidation currents consistently increase with the increase in Ni(II)(DMG) 2 loading, OH -, and alcohol concentrations. Rotating disk electrode results obtained with a Ni(II)(DMG) 2 coated graphite disk electrode showed that the electrocatalytic oxidation of alcohol is a 4-electron process producing formate anion (methanol oxidation) or acetate anion (ethanol oxidation). A mechanism for the electrocatalytic oxidation of methanol/ethanol was proposed, and a rate-determining step was also discussed.