Visible light driven nanocrystal anatase TiO2 doped by Ce from sol–gel method and its photoelectrochemical water splitting properties

Visible light driven nanocrystal anatase TiO2 was prepared by doping rare earth element Ce through sol–gel method. UV–Vis diffusion reflectance spectrum indicated its absorption edge extended to about 550 nm, red shifting about 170 nm compared with that without doping. Ce doping TiO2 showed obvious anodic photocurrent effect for water splitting under visible light irradiation (λ > 420 nm) in photoelectrochemical measurement with three electrodes configuration. Ce doping TiO2 showed higher photocurrent density than that of without doping TiO2 under full arc irradiation. Furthermore, the electronic structures for CeO2 and TiO2 were analyzed theoretically based on the first principle calculation. As a result, the electronic structure for Ce doping TiO2 is proposed as the overlap and some degree of hybridization among splitting occupied Ce 4f and unoccupied Ce 4f with O 2p and Ti 3d respectively. The visible light responsive property is mainly due to the transition from O 2p hybridizing with occupied Ce 4f to unoccupied Ce 4f overlapping with Ti 3d.