Surface Coordination Environment Engineering on Pt_xCu_1–x Alloy Catalysts for the Efficient Photocatalytic Reduction of CO₂ to CH₄

Alloy catalysts have been reported to be robust in catalyzing various heterogeneous reactions due to the synergistic effect between different metal atoms. In this work, aimed at understanding the effect of the coordination environment of surface atoms on the catalytic performance of alloy catalysts, a series of Pt x Cu 1– x alloy model catalysts supported on anatase-phase TiO 2 (Pt x Cu 1– x /Ti, x = 0.4, 0.5, 0.6, 0.8) were developed and applied in the classic photocatalytic CO 2 reduction reaction. According to the results of catalytic performance evaluation, it was found that the photocatalytic CO 2 reduction activity on Pt x Cu 1– x /Ti showed a volcanic change as a function of the Pt/Cu ratio, the highest CO 2 conversion was achieved on Pt 0.5 Cu 0.5 /Ti, with CH 4 as the main product. Further systematic characterizations and theoretical calculations revealed that the equimolar amounts of Pt and Cu in Pt 0.5 Cu 0.5 /Ti facilitated the generation of more Cu–Pt-paired sites (i.e., the higher coordination number of Pt–Cu), which would favor a bridge adsorption configuration of CO 2 and facilitate the electron transfer, thus resulting in the highest photocatalytic CO 2 reduction efficiency on Pt 0.5 Cu 0.5 /Ti. This work provided new insights into the design of excellent CO 2 reduction photocatalysts with high CH 4 selectivity from the perspective of surface coordination environment engineering on alloy catalysts.