Defect-engineering of tin oxide via (Cu, N) co-doping for electrocatalytic and photocatalytic CO2 reduction into formate

Electrocatalytic and photocatalytic reductions of CO2 into valuable chemicals or fuels have been considered a compelling strategy for environmental remediation and renewable energy conversion. In this field, SnO2 based materials have been widely applied as a promising electrocatalysts in the conversion of CO2 to formate, but the inferior catalytic efficiency is still the severe barrier for the application. In this study, a novel SnO2-based catalyst with Cu and N co-doping was designed for efficient and high-selective photoelectroreduction of CO2 into formate. XRD, FT-IR and XPS analyses demonstrated that (Cu, N) was doped into the lattice of SnO2 via replacing Sn and O, resulting the significant increase in the amount of oxygen deficiency from 27.18% to 36.72%. CV, LSV and EIS measurements proved that the (Cu, N) doping dramatically improved the photoelectrocatalytic performance of SnO2 based electrocatalysts for CO2 reduction. When the co-doping amount of (Cu, N) was 7 mol%, the Faradaic efficiency reached 54.97% with a lowest charge-transfer resistance and a fastest electron transfer rate. Furthermore, the DFT calculations revealed that the co-doping of Cu and N brought about the defect levels to narrow the band gap for the acceleration of the charge transfer, thereby improved the performances in electroreduction as well as photoreduction of CO2. (C) 2020 Elsevier Ltd. All rights reserved.