Boosting C2+ production from photoelectrochemical CO2 reduction on gallium doped Cu2O

Abstract

Photoelectrochemical CO2 reduction into C2+ products not only realizes the efficient conversion and utilization of CO2, but also provides a new way to synthesize value added hydrocarbons. However, it remains a grand challenge for highly selective synthesis of C2+ product due to the complexity of CO2 reduction and the coexistence of competitive reaction on the electrode surface. Herein we report a gallium doped Cu2O catalyst (Ga/Cu2O) prepared by a typical electrochemical deposition method via oriented growth on the surface of Cu mesh with easily controllable Ga contents. As the self-supporting electrode, it exhibits a highly efficient and selective CO2 reduction into C2+ products with Faradaic efficiencies of C2+, CH3CH2OH, and CH3CH2CH2OH as high as 20%, 6.5% and 6.64%, respectively at the potential of −1.8 V vs reversible hydrogen electrode (RHE). Experimental results show that Ga doping generated more oxygen vacancies via partial substitution in the lattice of Cu2O, resulting in rapid separation of the generated electron-hole pairs and regulating the electronic structure of catalyst surface and promotion of CO2 adsorption and activation. As a result, a higher *CO coverage and better C-C coupling probability on the surface of Ga/Cu2O were reached compared to those of unmodified Cu2O, which are responsible for the enhancement of the selectivity of CO2RR into C2+ products.