The anodic oxidation of carbon monoxide on gold in acid solutions

Abstract

The anodic oxidation of carbon monoxide on gold was studied in the oxide-free potential region, linear sweep voltammetry being used to minimize electrode poisoning. Only when p_co < c. 0.3 atm or when the reaction was inhibited by impurities were the plots of i against square root of scan rate linear. In other cases, i attained constant values at high scan rates; this is interpreted, together with other evidence, as due to the adsorption of CO prior to the start of the scan. Good Tafel plots were obtained under conditions where i was independent of scan rate, and the kinetic parameters are shown to be consistent with the Gilman reactant-pair mechanism. In the potential region of oxide formation on gold, the steady-state oxidation of CO proceeded with the formation of colloidal gold. The mechanism in this potential region was not investigated.