High-rate CO2-to-CH4 Electrosynthesis by Undercoordinated Cu Sites in Alkaline-Earth-Metal Perovskites with Strong Basicity

The electrochemical CO2 reduction to CH4 has been extensively demonstrated, but still suffers from relatively poor activity and requires high overpotentials especially at large electrolysis rates. Perovskite oxides (A(x)B(y)O) are one type of promising electrocatalyst for the CO2 reduction due to their tunable electronic structures. In this work, a Ca2CuO3 perovskite oxide catalyst is developed with alkaline-earth A-sites, featuring an inherently strong basic strengthand outstanding capability for CO2 adsorption, as well as the undercoordinated Cu sites generated through partial surface Ca2+ cation leaching. The Ca2CuO3 catalyst exhibitsa high partial current density of 517 +/- 23 mA cm(-2) for producing CH4 at a low applied potential of -0.30 V versus reversible hydrogen electrode, which further reached to a peak value of 1452 +/- 156 mA cm(-2). Density functional calculations show that the undercoordinated Cu sites allowed to promote the hydrogenation of *CO and subsequent *CHO intermediates, thus leading to the high CH4 activity. This work suggests an attractive design strategy for tuning the A-sites in perovskite oxides to realize high-rate CO2-to-CH4 electrosynthesis with low overpotentials.