Boosting photocatalytic CO2 reduction to CH3OH on TiO2 via AuCu alloy synergistic catalysis without sacrificial agent

Photocatalytic reduction of CO 2 to methanol using water as a proton source offers a sustainable pathway for solar energy storage and carbon neutrality. However, its practical application is hindered by low quantum efficiency, rapid charge recombination, and reliance on sacrificial agents. Herein, we developed a bimetallic AuCu alloy supported on TiO 2 nanoparticles (AuCu-TiO 2 ) via a NaBH 4 reduction method for efficient CO 2 -to-methanol conversion in the absence of sacrificial agents. The photocatalytic performance was correlated with in situ FTIR spectroscopy to unravel the synergistic roles of AuCu alloy sites and TiO 2 in mediating CO 2 reduction and H 2 O oxidation. CO 2 activation by photogenerated electrons leads to the formation of critical intermediates like COOH* and CHO*, which undergo sequential hydrogenation to produce methanol. The Au-Cu synergy facilitates the hydrogenation of COOH* to CHO*, significantly boosting methanol selectivity. By optimizing the AuCu loading and Cu/Au molar ratio, the AuCu-TiO 2 catalyst achieved a high methanol production rate of 63.31 μmol g −1 h −1 with 85.59 % selectivity. This work provides a general strategy for designing efficient bimetallic photocatalysts for selective CO 2 conversion under environmentally benign conditions.