Synergistic effect of N-Ho on photocatalytic CO2 reduction for N/Ho co-doped TiO2 nanorods

Abstract The photoreduction of CO2 by using Ho and N co-doped TiO2 was explored. The doping elements can further improve the separation efficiency of photogenerated electron-hole pairs via refining grains, causing lattice distortion and adsorbing more hydroxyl radicals(·OH). We found that there exists product selectivity such that the photoreduction products of Ho/N-TiO2 mainly consist of CO and methanol, while the counterparts of pristine TiO2 are CO and methane. The possible mechanism of CO2 reduction is depicted involving the generation and combination of specific radicals. Thus, the amount of ·OH adsorbed on the surface of the catalyst makes a significant difference in the selectivity in the reduction products. Ho/N-TiO2 catalyst with the synergic effect of Ho and N showed the best photoreductive performance for CO2 with H2O to CO and CH4, and its formation rate of CH4 was 29 μmol/gcatal./hour.