Metal–oxide heterointerface synergistic effects of copper–zinc systems for highly selective CO2-to-CH4 electrochemical conversion

Abstract

Carbon dioxide (CO₂) electrolysis presents a promising route for the conversion of CO₂ into value-added products. However, increasing selectivity for a specific deep-reduction product such as methane still remains a great challenge. Here, we report the highly efficient electroreduction of CO₂ to methane (CH₄) over a precisely controlled Cu–ZnO heterointerface system, which delivered superior activity with a faradaic efficiency of up to 72.4% at −0.7 V vs. RHE, surpassing most previously reported catalysts. Experimental measurements and theoretical calculations confirmed the high CO₂ to CH₄ selectivity was derived from the interfacial synergistic effects between the Cu and ZnO nanostructure. DFT calculations showed that the electronic structure of the interfacial Cu sites was significantly modulated by ZnO, resulting in moderate adsorption energies of *COOH and *CHO intermediates on the Cu sites, in turn, promoting the conversion from CO₂ to CH₄. This work unravels the strong dependence of CO₂-reduction selectivity on the heterointerfaces and provides a platform for designing highly selective electrochemical catalysts.