LONG-TERM ACTIVATION OF THE COPPER CATHODE IN THE COURSE OF CO2 REDUCTION

The cathodic reduction of CO2 at copper electrodes in aqueous solutions of bicarbonates was investigated with special attention directed towards the changes in the current efficiency of the principal products (CH4, C2H4, C2H5OH) as a function of the electrolysis duration. A severe deactivation of the copper cathode, starting usually 20-30 min after the beginning of the electrolysis run, is shown to be little affected by the pre-electrolysis of the solution as well as by the nature of the electrode pretreatment. A periodic anodic activation procedure is described which, when applied to the copper cathode, allows high hydrocarbon yields to be maintained over prolonged electrolysis runs.