Selective CO 2 electroreduction to formate over a Cu-based catalyst in S 2- -containing electrolyte.

A Cu 2 O-derived catalyst selectively and durably electroreduces CO 2 to formate with a maximum faradaic efficiency of 74% in S 2- -containing electrolyte and exhibits a high formate partial current density of up to 110 mA cm -2 in a flow cell.