Doping effect from Ag and Sb in KBiO3 photocatalyst: first principles study

The direct band gap of cubic KBiO3 with space group Pn-3 calculated from the standard density functional theory (DFT) within the Perdew–Burke–Ernzerhof functional is ∼0·54 eV and obviously underestimated in comparison with the experimental value of 2·1 eV. Using the Heyd–Scuseria–Ernzerhof hybrid functional, the band gap can be corrected to ∼1·77 eV. Further, first principles calculations on Ag/Sb doped KBiO3 indicate that a flexible band gap can be obtained by adjusting the amount of Ag and Sb doping in KBiO3. In particular, K0·667Ag0·333Bi0·5Sb0·5O3 has a DFT band gap of 0·61 eV and larger dispersion at the bottom of the conduction band with smaller effective electron masses, which would lead to an enhancement in photocatalytic activity in comparison with pure KBiO3.