Electronic properties of highly-active Ag3AsO4 photocatalyst and its band gap modulation: an insight from hybrid-density functional calculations

Abstract

The electronic structures of highly active Ag-based oxide photocatalysts Ag₃AsO₄ and Ag₃PO₄ are studied by hybrid-density functional calculations. It is revealed that Ag₃AsO₄ and Ag₃PO₄ are indirect band gap semiconductors. The Hartree–Fock mixing parameters are fitted for experimental band gaps of Ag₃AsO₄ (1.88 eV) and Ag₃PO₄ (2.43 eV). The smaller electron effective mass and the lower valence band edge of Ag₃AsO₄ are likely to be responsible for the superior photocatalytic oxidation reaction to Ag₃PO₄. The comparable lattice constant and analogous crystal structure between the two materials allow the opportunities of fine-tuning the band gap of Ag₃As_xP_1−xO₄ using a solid-solution approach. The development of Ag₃As_xP_1−xO₄ should be promising for the discovery of novel visible-light sensitized photocatalysts.