Dual redox-active sites with synergistic spin polarization effect to facilitate overall CO2 photoreduction with H2O

Photocatalytic CO 2 reduction comprises two coupled half-reactions: CO 2 reduction and H 2 O oxidation. Efficient coupling of these reactions maximizes the utilization of photogenerated electrons and holes, enhancing CO 2 conversion and product selectivity. In this study, sulfur-deficient V S -Zn 3 In 2 S 6 (V S -ZIS) catalysts were synthesized via an ethylene glycol solvothermal method, followed by anchoring Fe single-atom sites (Fe/V S -ZIS) to facilitate CO 2 photoreduction using H 2 O as proton source. The 1 %Fe/V S -ZIS exhibited exceptional performance, with a CO production rate of 88.6 μmol·g −1 ·h −1 and 97 % selectivity. Experimental and DFT results revealed that V S functioned as reductive sites to strengthen CO 2 adsorption and activation, while Fe single atoms (SAs) served as oxidative sites to facilitate H 2 O dissociation for proton supply. Fe SAs also induced spin polarization to enhance IEF, thereby suppressing photogenerated charges recombination at redox sites. Meanwhile, Fe SAs reduced COOH* formation energy barrier and lowered CO desorption temperature, improving CO selectivity. The constructed dual active sites synergistically enhanced the overall photocatalytic CO 2 reduction performance. This work offers new technical pathways for designing redox dual-active sites to boost the overall photocatalytic CO 2 reduction efficiency.