Abstract: Electronic structures and optical properties of intrinsic α-Bi₂O₃, La-doped, oxygen vacancy doped, and co-doped systems were studied by first-principles method based on density functional theory, in order to obtain α-Bi₂O₃ photocatalytic materials with excellent performance. The results show that the structure of the doped system is less distorted, and the oxygen vacancy (V_O) doped and La-V_O co-doped systems have band gaps of both valence band and conduction band shifted down and impurity energy levels introduced in band gaps, indicating that doping can reduce the energy required for electron excitation from valence band to conduction band, which is beneficial to the electron leap. In particular, the La-V_O co-doping makes the impurity energy level close to conduction band bottom compared to the oxygen vacancy single doping, and this tendency may make the recombination defect more likely to be the capturing center of photogenerated electrons than the recombination center of photogenerated electron-hole pairs. At the same time, La-V_O co-doping leads to the increase of the curvature of band bending near the conduction band bottom, that is, the enhancement of the dispersion relationship, which reduces the effective mass of electrons and accelerates the movement of electrons. Therefore, La-V_O co-doping can greatly improve the effective separation of photogenerated electron-hole pairs. On the other hand, La-V_O co-doping, while significantly extending the visible light absorption range, also greatly enhances the visible light absorption intensity. Therefore, La-V_O co-doping can effectively improve the photocatalytic activity of α-Bi₂O₃. This study provides a new idea for improving the performance of other photocatalytic materials by using rare earth ion doping.

Key words: α-Bi₂O₃, photocatalytic material, La-V_O co-doping, oxygen vacancy, electronic structure, optical property, first-principle