Construction of Z-scheme Ag3PO4/Bi2WO6 composite with excellent visible-light photodegradation activity for removal of organic contaminants

Abstract

Ag3PO4 has good potential for use in photocatalytic degradation of organic contaminants. However, the activity and stability of Ag3PO4 is hard to sustain because of photocorrosion and the positive potential of the conduction band of Ag3PO4. In this study, A composite consisting of Bi2WO6 nanosheets and Ag3PO4 was developed to curb recombination of charge carriers and enhance the activity and stability of the catalyst. Formation of a Ag3PO4/Bi2WO6 composite was confirmed using X-ray diffraction, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Photoluminescence spectroscopy provided convincing evidence that compositing Bi2WO6 with Ag3PO4 effectively reduced photocorrosion of Ag3PO4. The Ag3PO4/Bi2WO6 composite gave a high photocatalytic performance in photodegradation of methylene blue. A degradation rate of 0.61 min−1 was achieved; this is 1.3 and 6.0 times higher than those achieved using Ag3PO4 (0.47 min−1) and Bi2WO6 (0.10 min−1), respectively. Reactive species trapping experiments using the Ag3PO4/Bi2WO6 composite showed that holes, ·OH, and ·O2− all played specific roles in the photodegradation process. The photocatalytic mechanism was investigated and a Z-scheme was proposed as a plausible mechanism.