Stable Cu+/Cu2+ species derived from in-situ growing Cu-S-V bonds in CuVxS electrocatalysts enables high efficiency CO2 electroreduction to methanol

Regulating oxidation state of Cu-based chalcogenides catalysts during electrolysis is of great significance for efficient CO2 electrochemical reduction reaction (CO2RR) to methanol, which still remains a dramatic challenge. Herein, we construct a heterogeneous Cu3VS4/CuS electrocatalyst (denoted as CuVxS), in which the in-situ growing Cu-S-V bonds avoid the accumulated electrons on oxidized Cu sites and inhibit the deep reduction of CuS to metallic Cu during electrolysis, maintaining stable and abundant reactive Cu+/Cu2+ species to promote CO2RR performance to methanol. By this design, the CuV0.1S catalyst achieves an ultrahigh methanol selectivity of 79.8 %. In-situ FTIR measurement reveals that the synergistic effect of Cu+/Cu2+ species and Cu-S-V bonding facilitates the *CO adsorption and the subsequent *CO hydrogenation process, which improve the generation of *CHO and *OCH3 intermediates for enhanced methanol selectivity. This work provides a new insight into stabilizing high oxidation state of Cu-based electrocatalyst to maintain sufficient active sites for CO2RR.