Defect-mediated electron pumping at heterointerfaces boosts CO2-to-fuels conversion

Developing CO 2 electroreduction (CO 2 RR) catalysts that exhibit high activity, selectivity, and long-term stability is a crucial challenge in the pursuit of carbon-neutral energy systems. In this work, we had engineered a Ruddlesden-Popper (RP) perovskite/CuO heterostructure catalyst with remarkable CO 2 RR performance. By strategically modulating the valence of the A-site, the performances of the catalyst were optimized through tailored surface/interface oxygen vacancies (Ovs). The optimized La 1.9 CuO 4 /CuO catalyst achieved a CO Faradaic efficiency (FE CO ) of 97.54 % at −0.8 V vs. RHE and demonstrated stability for over 48 h during continuous testing. Mechanism research combining experimental analysis and density functional theory (DFT) calculations revealed that the heterojunction directionally accumulated electrons to the copper oxide domains, forming a distinctive "electron pumping" that promoted CO 2 activation and lowered the Gibbs free energy barrier for carboxyl intermediate formation, thereby enhancing its binding capability in the CO 2 RR. Concurrently, Ovs enhanced CO 2 activation kinetics and stabilized the ∗CO intermediate. A Ovs-rich La 1.9 CuO 4 /CuO heterostructured electrocatalyst have been successfully synthesized. The La 1.9 CuO 4 /CuO provides abundant active sites for efficient electron transfer. The charge redistribution at the p-n heterojunction interface established a stable electron-rich built-in electric field, creating a unique "electron pump" effect that modulated the adsorption strength of critical intermediates and optimized the energy barriers for adsorption, thereby significantly enhancing CO 2 reduction activity. Simultaneously, the oxygen defect sites stabilized key reaction intermediates through strong electronic coupling, further optimizing the catalytic system while suppressing the competing HER. • A defect-engineered RP-perovskite/CuO heterojunction catalyst was successfully constructed. • The heterogeneously defective perovskite catalyst exhibited outstanding electrocatalytic performance in CO 2 RR. • In situ Raman and DFT calculations revealed the catalytic mechanism of the Ovs-rich La 1.9 CuO 4 /CuO heterojunction. • The synergy of oxygen vacancies and heterojunction enhanced CO 2 RR selectivity while suppressing HER.