Investigation of W/Mo co-doping with multiple concentrations in photocatalyst BiVO4 by first-principles calculations

Monoclinic BiVO4, being a multicomponent metal oxide, exhibits superior solar-active performance than its tetragonal phase in photocatalysis. In order to obtain improved separations between photoinduced electrons and holes, electronic properties and photocatalytic activity of W/Mo co-doped BiVO4 with multiple W/Mo concentrations (W–αMo–BiVO4 and βW–Mo–BiVO4 (α,β=1,2,3)) were investigated using the GGA + U method based on density functional theory (DFT). According to the calculated formation energy, W–αMo–BiVO4 composition is more stable than βW–Mo–BiVO4 if the amount of α is equal to β. The electronic structures of W–αMo–BiVO4 and βW–Mo–BiVO4 (α,β=1,2,3) tend to have sharper valence band and flatter conduction band edges than those of pure BiVO4. Multiple co-doping W/Mo configurations result in the formation of continuous impurity states, which is beneficial for photocatalysis response. Notably, the absorption peaks of W–αMo–BiVO4 and βW–Mo–BiVO4 (α,β=1,2,3) emerge at the dominant photon flux segment corresponding to 0–1.23 eV, improving the solar light absorption and conversion. Moreover, the results of dielectric constant and carrier effective mass indicate that W and Mo co-doping with different concentrations in BiVO4 substantially enhance the separation of photoactive electron-hole pairs and the mobility velocities of charge carriers. The potentials vs. NHE strongly confirmed that W–αMo–BiVO4 and βW–Mo–BiVO4 (α,β=2,3) have abundant reduction potential to strengthen the capability of converting photogenerated e− into H2O2. Particularly, ECB (+0.43 eV vs. NHE) of 2W–Mo–BiVO4 possesses a more powerful reduction capability. Based on our results, W/Mo co-doping with multiple concentrations in BiVO4 (W–αMo–BiVO4 and βW–Mo–BiVO4 (α,β=2,3)) are particularly suitable for solar-light-driven photocatalytic activity.