Kinetic model of ethanol oxidation on Ni-Mo alloy electrode

Abstract

Ni-Mo alloy electrode, prepared by electrodeposition, were characterized for application to ethanol oxidation in 1 mol.L-1 KOH solution. Their electrochemical behavior was studied using cyclic voltammograms and quasi-steady-state current-potential curves. A mathematical model was developed to predict the behavior of ethanol oxidation on Ni-Mo alloy electrodes. The redox of Ni(OH)(2)/NiOOH couples in the alkaline solution is a preludial step for the ethanol electrooxidation, and the rate constants related to this reaction, k(1) as well k(-1), are functions of applied potential. Ethanol oxidation is carried out by a chemical reaction with rate constant k(Cl). The kinetic equations were derived and the kinetic parameters were obtained from a comparison of experimental results with kinetic equations. The rate constants of electrochemical reactions could be expressed as k(1) (E) = 1.41 x 10(7)exp(0.5 FE/RT) mmol.cm(-2).s(-1), k(-1) (E) = 0.711 exp(0.5 FE/RT) mmol.cm(-2).s(-1), in which E was the applied potential vs SCE, and the chemical reaction rate constant, k(Cl), was 1.99 x 10(-4)cm.s(-1).