Mechanisms for Highly Efficient Mineralization of Bisphenol A by Heterostructured Ag2WO4/Ag3PO4 under Simulated Solar Light

The application of Ag3PO4 as a commonly used photocatalyst is limited by its high recombination potency and electron–hole pairs with weak redox potential. It is significant to enhance the photocatalytic activity of Ag3PO4 by coupling with a wide band gap semiconductor. In this study, Ag2WO4 was selected to promote the photocatalysis of Ag3PO4 giving that it has wide band gap energy and strong redox potential. A facile chemical precipitation method was applied to assemble Ag2WO4 nanoparticles on the surface of Ag3PO4 to form an Ag2WO4/Ag3PO4 heterojunction. The Ag2WO4/Ag3PO4 heterojunction containing 7.5% molar mass of WO42– (7.5W) displayed the most superior photocatalytic efficiency under simulated solar light irradiation: 93% of bisphenol A was degraded just within 10 min and above 75% was mineralized within 30 min. The degradation reaction rate constant was 3 times higher than that of the pure Ag3PO4. The excited high-level-energy electrons on the conduction band of Ag3PO4 would transfer thermodynamically to the conduction band of Ag2WO4, and the generated valence band holes on Ag2WO4 easily shifted to the low-energy valence band of Ag3PO4, resulting in high separation of electron–hole pairs. The photogenerated holes and superoxide radical species played predominant roles in the reaction system.