Reversed Electron Transfer in Dual Single Atom Catalyst for Boosted Photoreduction of CO₂

Photogenerated charge localization on material surfaces significantly affects photocatalytic performance, especially for multi-electron CO2 reduction. Dual single atom (DSA) catalysts with flexibly designed reactive sites have received significant research attention for CO2 photoreduction. However, the charge transfer mechanism in DSA catalysts remains poorly understood. Here, for the first time, a reversed electron transfer mechanism on Au and Co DSA catalysts is reported. In situ characterizations confirm that for CdS nanoparticles (NPs) loaded with Co or Au single atoms, photogenerated electrons are localized around the single atom of Co or Au. In DSA catalysts, however, electrons are delocalized from Au and accumulate around Co atoms. Importantly, combined advanced spectroscopic findings and theoretical computation evidence that this reversed electron transfer in Au/Co DSA boosts charge redistribution and activation of CO2 molecules, leading to highly significantly increased photocatalytic CO2 reduction, for example, Au/Co DSA loaded CdS exhibits, respectively, approximate to 2800% and 700% greater yields for CO and CH4 compared with that for CdS alone. Reversed electron transfer in DSA can be used for practical design for charge redistribution and to boost photoreduction of CO2. Findings will be of benefit to researchers and manufacturers in DSA-loaded catalysts for the generation of solar fuels.