The controllable mutual transformation of Ag⁺/Ag⁰ pairs in Ag₃PO₄/Bi₂MoO₆ toward the high catalytic efficiency and durable reusability

A series of Ag₃PO₄/Bi₂MoO₆ p–n heterojunctions were assembled via the thin Bi₂MoO₆ nanosheets attached to the surface of rhombic dodecahedral Ag₃PO₄. The self-optimized Ag⁺/Ag⁰ pairs existed in the as-prepared heterojunction which are regarded as charge transmission bridge to accelerate the reaction. The samples presented much higher photocatalytic activity for the degradation of the target pollutions (completely degradation under solar light illuminating of 70 min for rhodamine B, 80 min for aureomycin and 70 min for tetracycline). It was found during the recycle test, photocatalytic performance of Ag₃PO₄/Bi₂MoO₆ underwent a successive increase since the second cycle in which the completely degradation of RhB was achieved after only 60 min visible light irradiation, confirming the composite is reusable with well stability. The oxidative mechanism was carefully investigation based on the scavengers trapping test, ESR spectra, XPS spectrum, photocurrent responses, and electrochemical impedance spectroscopy analysis. It proved Ag⁰ gradually generated from the as-prepared composite under solar light illuminating is fixed at an optimized content. The charge transfer was consequentially enhanced during the suitable level turning of Ag⁺/Ag⁰ pairs. Mediated by Ag⁰ sandwiched in p–n junction, the active species of the present photooxidative reaction experienced various period from ^·OH and h⁺ in the initial reaction to the additional ^·O₂⁻ in the successive recycle experiment owing to generation of the rectifying contact and Schottky junction. This study provides a new cognition for the improved reusability of the photocorrosion materials via the mutual transformation of metal monomers and ions.