Improvement of the selectivity of the electrochemical conversion of CO2 to hydrocarbons using cupreous electrodes with in-situ oxidation by oxygen

It is still a challenge to find catalysts for the selective electrochemical reduction of CO 2 to value added products. We present a new method for the in-situ modification of a copper catalyst by adding oxygen to the reactant gas. With an appropriate process procedure consisting of a sequence of electrolysis and purge steps, a Cu 2 O layer was formed during the purge steps. When it was reduced again during the next electrolysis step, Cu + species remained stable on the surface and let to a higher faradaic efficiency for C 2 H 4 formation and even a lower onset potential for CO 2 reduction in general. This effect was observed for a wide range of O 2 content from 10 % to 60 % in the reactant gas. In comparison to electrolysis with pure CO 2 , formation of methane was largely suppressed.