The electrochemical oxidation of carbon monoxide at gold electrodes in alkaline solutions has been studied by chronopotentiometric and galvanostatic methods. The rate of the oxidation has been found to be first order in CO concentration and first order in hydroxyl-ion concentration, indicating that the two species rapidly form an electro-active species. The electrolysis, which gives carbonate ion as a final product, is totally irreversible. The kinetic parameters have been evaluated for a wide range of solution conditions; for an activated gold electrode the mean value for (1 --con, is 0"50 + 0-02 and the mean value for the simple heterogeneous rate constant, k,,h, is 3 Γ 10 -9 cm. l/mole.s. Mechanisms consistent with the experimental data are proposed; these include a oneelectron rate-controlling step leading to a radical intermediate.
R6sum~---Etudes par chronopotentiometrie et gaivanostatie de l'oxydation 61ectrochimique de CO, en solution alcaline et sur 61ectrode Au. La vitesse est du premier ordre par rapport A [CO] et/L [OH-], ce qui indique que ces deux esl~w.es engendrent rapidement des esl~,~ 61ectroactives. L'61ectrolyse fournissant COs e-au bilan, est totalement irr6versible. Les param~tres cin6tiques ont 6t6 6valu6s dans un champ 6tendu de conditions de la solution: pour une 61ectrode Au active, la valeur moyenne de (1 --~)na est 0,50 4-0,02 et la valeur moyenne de la constante de vitesse, k,,~, est 3 β’ 10 -9 cm.1/mole. L'on sugg~re des m~:anismes plausibles, en particulier une 6tape r6gulatrice ~t un 61ectron engendrant un radical interm6diaire.