Surface Hydroxyl Group Embedding and CuAg Alloy Anchoring Promotes Photocatalytic CO2 Reduction of Hollow TiO2 Nanostructures

Converting greenhouse gas into hydrocarbon fuels with high efficiency by photocatalysis possesses a huge challenge because of the slow charge transfer and lack of surface-active sites. Herein, hydroxyl group-enriched hollow TiO2 with CuAg alloy loading was constructed by solvothermal treatment for CO2 photoreduction. The hollow structure could improve light harvesting and facilitate charge transfer, while the solvothermal treatment-induced surface hydroxyl groups could enhance the CO2 adsorption ability, which was confirmed by CO2-TPD analysis. The CuAg alloy not only promoted charge separation through a Schottky junction but also provided abundant active sites for CO2 activation. Photocatalytic tests showed that the 4 wt % CuAg loading achieved the highest CO2 conversion efficiency of TiO2. Moreover, in situ FT-IR result revealed the formation of key intermediates such as HCO3– during activation of CO2 on the surface of TiO2. This study could offer a rational strategy to cooperatively optimize the surface property and alloy cocatalyst loading of TiO2-based photocatalysts and pave the way for efficient CO2 conversion.