PtCu alloy cocatalysts for efficient photocatalytic CO2 reduction into CH4 with 100% selectivity†

Abstract

In this paper, PtCu alloys with varying Pt/Cu ratios were deposited onto TiO₂ nanocrystals to selectively photoreduce CO₂ into CH₄. The experimental results show that the appropriate Pt/Cu deposition ratio significantly improves CH₄ production with 100% selectivity. The PtCu alloy not only effectively promotes the separation/transfer of photogenerated charges, but is also beneficial for the adsorption of CO₂ and the formation and activation of intermediates (CO₂⁻, *COOH, *CO, and *CHO). Furthermore, two paths for *CO formation are observed on the surface of PtCu/TiO₂, providing sufficient *CO for CH₄ generation. Density functional theory calculations show that the synergistic effect of PtCu reduces the activation energy barriers of *CO₂ and *CHO and inhibits the desorption of *CO, which simultaneously optimizes the efficiency and selectivity of CO₂ reduction. These findings may provide new insights for exploring alloy cocatalysts for regulating the product selectivity of photocatalytic CO₂ reduction.