Cu surface doped TiO2: Constructing Cu single-atoms active sites and broadening the photo-response range for efficient photocatalytic hydrogen production

Photocatalysts loaded with suitable metal single atoms (SAs) have high catalytic activity due to the maximum exposure, which have excellent potential for photocatalytic hydrogen production. However, it cannot regulate the bandgap of support if the metal SAs are only exposed on the surface. Herein, combining the high activity of SAs with the bandgap regulation of doping, we proposed a metal surface doping strategy to construct Cu single-atoms TiO2 (CuSAs-TiO2). The surface anchored Cu atoms can effectively capture photogenerated electrons to reduce H intermediates, while the underneath doped Cu atoms can reduce the bandgap of TiO2 to broaden the photo-response range and improve the photoelectric response rate. Under the irradiation of light with wavelengths of 365, 385 and 420 nm, the apparent quantum efficiencies are all zero for pure TiO2, while that of the optimal CuSAs-TiO2 are 6.03%, 0.84% and 0.04%, respectively. Theoretical simulation is consistent with the experiments, and the interaction between the underneath doped Cu and the surface anchored Cu can improve the adsorption–desorption equilibrium of H intermediates and optimize hydrogen evolution kinetics. This work provides a feasible strategy for designing visible light-responsive single-atoms photocatalysts by combining the advantages of metal SAs and doping.