Effects of Mo concentration on photocatalytic activity of Mo-doped BiVO4 from first-principles calculations
In this paper,the electronic structures,optical properties and photocatalytic performances of Mo doped into V-site of BiVO4 with different concentrations were investigated using the first nature principles based on density generalized function theory.The results of the defect formation energy calculations indicate that all three doping systems of BiMoxV1-xO4(x=0.0625,0.125,0.25)are stable.The electronic structure calculations show that the band gaps of the four systems of BiMoxV1-xO4(x=0,0.0625,0.125,0.25)are 2.123 eV,2.142 eV,2.160 eV and 2.213 eV,respectively.The band gap values of the doped BiVO4 system are all larger than that of the intrinsic BiVO4,and the band gap increases with the increase of Mo concentration.The energy band structures of the three doped systems BiMoxV1-xO4(x=0.0625,0.125,0.25)are all shifted to the lower energy region,resulting in the doped system conduction band bottom crossing the Fermi energy level,and Mo doped BiVO4 has n-type semiconductor properties.Optical property calculations show that dielectric constants of the intrinsic BiVO4 and three doped systems BiMoxV1-xO4(x=0.0625,0.125,0.25)are 3.08,3.90,12.7 and 17.50,respectively,and the static dielectric constants show an increasing trend after doping.The reflection co-efficients and the imaginary parts of the dielectric functions for the three doped BiVO4 systems are significantly enhanced in the low-energy region,and the light absorption coefficients of three Mo-doped BiVO4 systems are significantly enhanced for infrared light.The photocatalytic performance calculations showed that the intrinsic Bi-VO4 oxidation of H2O to O2is the weakest and the BiMo0.25 V0.75O4 oxidation of H2O to O2 is the strongest.
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