Construction and mechanism of a highly efficient and stable Z-scheme Ag3PO4/reduced graphene oxide/Bi2MoO6 visible-light photocatalyst

A novel Ag3PO4/reduced graphene oxide/Bi2MoO6 (Ag3PO4/RGO/Bi2MoO6) Z-scheme photocatalyst has been successfully prepared by a precipitation-solvothermal method. The composition, morphology, structure and optical properties of the ternary composite were thoroughly investigated. The obtained Ag3PO4/RGO/Bi2MoO6 composite displayed significantly enhanced photocatalytic activity for the degradation of methylene blue (MB) under visible light irradiation, and its degradation rate (0.14575 min(-1)) was approximately 2.34, 2.63 and 4.97 times faster than that of the Ag3PO4/Bi2MoO6 composite, pure Ag3PO4 and Bi2MoO6, respectively. Meanwhile, the Ag3PO4/RGO/Bi2MoO6 composite exhibited better stability compared with pure Ag3PO4 after four consecutive reuses. In addition, it shows good photodegradation efficiency for five other dyes under visible light irradiation. The improved photocatalytic performance and stability could be ascribed to the larger surface area, extended visible-light absorption capability and high-efficiency separation of electron-hole pairs of the Ag3PO4/RGO/Bi2MoO6 composite. Furthermore, RGO could act as a charge transmission bridge to accelerate the electron transfer from Ag3PO4 to Bi2MoO6 (Ag3PO4 center dot RGO center dot Bi2MoO6) in this Z-scheme system; thus the photocorrosion of Ag3PO4 and the recombination of charge carriers were effectively suppressed. The energy band structure and free radical capturing experiments proved that the electrons in the conduction band (CB) of Bi2MoO6 had stronger reducibility and the holes in the valence band (VB) of Ag3PO4 had higher oxidizability. Simultaneously, combined with the results of PL spectroscopy and photoelectrochemical measurements, the mechanism of Z-scheme charge transfer in the Ag3PO4/RGO/Bi2MoO6 composite was further confirmed. This study provides an idea for improving the anti-photocorrosion and photocatalytic performance of photosensitive semiconductors.