Synergistic integration of bimetallic PtCu alloy modulating proton supply for efficient artificial photosynthesis of methanol

Photocatalytic CO₂ reduction with H₂O into valuable solar fuels is a huge potential to alleviate carbon emissions and energy issues. However, selective photocatalytic CO₂ reduction with H₂O into desired chemicals is still a grand challenge owing to the unfavorable kinetics of multistep proton-coupled electrons. Herein, we employed a facile photo-deposition strategy to load Pt-Cu alloy over BiOBr_1−xCl_x (BOBC) for CO₂ photoreduction with H₂O as a proton donor. The optimal Pt-Cu/BOBC with Pt-Cu pair sites exhibited a remarkable performance of CO₂ photoreduction yielding CH₃OH of 16.52 μmol·g⁻¹·h⁻¹ with 97.14 % electron-based selectivity. The experimental and theoretical analysis revealed the synergistic effect of Pt-Cu pair sites in BOBC, which enabled Pt to promote the formation of protons from dissociated H₂O while Cu accelerate the protonation of CO₂, thus advancing the highly selective production of CH₃OH. This work highlighted the role of proton supply from H₂O oxidation to promote the kinetics of CO₂ protonation during photocatalytic reaction.