Surface Coordination Environment Engineering on PtxCu1- x Alloy Catalysts for the Efficient Photocatalytic Reduction of CO2 to CH4

Abstract

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_xCu_1-x alloy model catalysts supported on anatase-phase TiO₂ (Pt_xCu_1-x/Ti, x = 0.4, 0.5, 0.6, 0.8) were developed and applied in the classic photocatalytic CO₂ reduction reaction. According to the results of catalytic performance evaluation, it was found that the photocatalytic CO₂ reduction activity on Pt_xCu_1-x/Ti showed a volcanic change as a function of the Pt/Cu ratio, the highest CO₂ conversion was achieved on Pt_0.5Cu_0.5/Ti, with CH₄ as the main product. Further systematic characterizations and theoretical calculations revealed that the equimolar amounts of Pt and Cu in Pt_0.5Cu_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 CO₂ and facilitate the electron transfer, thus resulting in the highest photocatalytic CO₂ reduction efficiency on Pt_0.5Cu_0.5/Ti. This work provided new insights into the design of excellent CO₂ reduction photocatalysts with high CH₄ selectivity from the perspective of surface coordination environment engineering on alloy catalysts.

Keywords: Cu−Pt-paired sites; PtxCu1−x alloy; adsorption configuration; coordination environment; photocatalytic CO2 reduction.