Defect rich copper oxide nanosheets for selective electrochemical conversion of CO2 to multi-carbon products at high current density

Abstract Highly selective electrochemical reduction of CO2 (CO2RR) to multi-carbon (C2+) products at high current density remains a big challenge. Herein we report copper oxide nanosheets (CuO-st) for selective electrochemical conversion of CO2 to C2+ products at high current density. Benefiting from the defect-rich structure verified by HR-TEM and XPS characterization and the designed gas diffusion electrode, such a CuO-st material exhibits CO2RR FE (C2+) of 86 and 80 % at 1.0 and 1.8 A cm−2, respectively, with excellent durability of 50 h @ 500mAcm−2 and storable lifetime for >10 months. Importantly, using quasi-situ XPS and in-situ Roman spectra, we have shown the first evidence for the presence of Cu (ǀ) during the eCO2RR on initial Cu (ǁ) material, and the proportion of Cu (ǀ) varies with the reaction current density. The rough and defective surface of CuO-st serves as a favorable reservoir to produce enough Cu (ǀ) to assist the C-C coupling, thus achieving selective CO2RR to C2+ products at high current density. Our study not only provides a new insight into CO2RR, but also suggests that in-situ forming active species from stable Cu (ǁ) materials during the reaction may be a good choice for the practical application, which will be very helpful to the development of cost-effective CO2RR electrocatalysts.