Incorporating highly dispersed and stable Cu+ into TiO2 lattice for enhanced photocatalytic CO2 reduction with water

Cu-based catalysts have been widely studied for photocatalytic CO2 reduction; however, the role of Cu species is still ambiguous because they exist in multiple forms, which can possibly interchange between themselves. In this paper, highly dispersed Cu+ was incorporated into a TiO2 lattice through a flame spray pyrolysis (FSP) route, and it exhibited excellent activity and stability for photocatalytic CO2 reduction. The highest CO and CH4 yields were obtained on CuTi-1, reaching 43.5 and 16.7 μmol g−1 after 4 h of irradiation, which are 2.8 times and 8.4 times higher than those of pristine TiO2, respectively. After three cycles, the activity of CuTi-1 only slightly decreased. The highly dispersed Cu+ ions in the TiO2 lattice were very stable, and they effectively slowed the recombination of the photoinduced charges, which was confirmed by XPS and PL analyses. Meanwhile, the Cu+ ions in the TiO2 lattice promoted the adsorption and activation of CO2 and served as the active sites for CO2 photoreduction.