Synthesis of AgBr/Ag4P2O7 composite photocatalyst and enhanced photocatalytic performance

Ag4P2O7 and AgBr/Ag4P2O7 photocatalysts were synthesized by a simple precipitation reaction, and their structures were characterized by X-ray powder diffraction, scanning electronic microscopy, Brunauer–Emmett–Teller surface area analysis, X-ray photoemission spectroscopy, UV–vis absorption spectroscopy, photoluminescence, and surface photovoltage techniques. Photocatalytic degradations of methylene blue over Ag4P2O7 and AgBr/Ag4P2O7 were also studied under visible light irradiation. AgBr/Ag4P2O7 exhibited excellent photocatalytic efficiency, with the activity higher than that of Ag4P2O7. The band gap and valence band of Ag4P2O7 were 2.67 eV and 1.93 eV, respectively. Ag4P2O7 failed to produce OH radicals by directly oxidizing OH− because the oxidation potential of OH− was 2.7 eV. Therefore, electrons excited by light reacted with O2 to produce O2− radicals that then formed OH radicals. Finally, OH radicals oxidized MB molecules. The matching energy bands of Ag4P2O7 and AgBr in the AgBr/Ag4P2O7 heterocatalysts effectively separated the photo-induced charges, which may enhance the photocatalytic activity of Ag4P2O7.