First-principles study on the photocatalytic properties of Cr-doped Cu₂O

It was found in recent years that inorganic semiconductor materials exhibited excellent photocatalytic performance and had broad application prospects in environmental treatment and energy conversion; in this aspect, Cu₂O semiconductor has attracted extensive attention owing its superior adsorption capacity for oxygen and high photo absorption coefficient. Considering that doping in Cu₂O could improve its photocatalytic efficiency in the visible region, in this work, the formation energy, electronic structure, and photocatalytic properties of Cu₂O doped with different concentrations of Cr were investigated by first-principle calculation. The results indicate that intrinsic Cu₂O shows semiconductor properties and the absorption of visible-light is weak; after doping with different concentrations of Cr and in different positions, the Cr-doped Cu₂O system are all stable and show metallic characteristics. Compared with intrinsic Cu₂O, the absorption peaks of Cr-doped Cu₂O in the visible-light range are enhanced. When two Cr atoms are doped in the nearest neighbor configuration, the absorption coefficient in the visible-light region is the largest, with the strongest photocatalytic efficiency. The density of states shows that the visible-light absorption of Cr-doped Cu₂O systems is mainly induced by the intra-band transition of electrons in Cr 3d states. The doping concentration and configuration influence mainly the physical properties of Cu₂O in the long wavelength range, but have little effect in the short wavelength range. Therefore, an increase in the doping concentration of Cr dopants and a change in the configuration can improve its photocatalytic efficiency in the visible region, and then promote the progress of Cu₂O application in photocatalysis.