Synthesis of Ag3 VO4 /Bi2 WO6 heterojunction photocatalyst with enhanced photocatalytic activity under visible light irradiation by hydrothermal methods.

Ag₃ VO₄ (AVO)/Bi₂ WO₆ (BWO) composites with different AVO/BWO molar ratios were synthesized using a single-step hydrothermal method. The photocatalytic performance of the synthesized photocatalysts in the degradation of C.I. Reactive Red 2 (RR2) under visible light (Vis.) irradiation was evaluated. The AVO/BWO composites were characterized by X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible (UV-Vis) spectroscopy, photoluminescence spectroscopy, Brunauer–Emmett–Teller analysis and X-ray photoelectron spectroscopy. Scavenger experiments were performed to determine the photocatalytic mechanism. The AVO/BWO composites exhibited much greater photocatalytic efficiency than pure AVO and BWO; moreover, AVO/BWO molar ratio of 1/3 (AB3) yielded the best photo-activity. AB3 exhibited the greatest photocatalytic performance, with RR2 removal efficiencies of 82% and 92% under Vis. and solar irradiations, respectively. The RR2 photodegradation rate constant of AB3 was 0.0894 min^–1, which was about 13.5 and 16.9 times those of AVO and BWO under Vis. irradiation, respectively. The excellent photo-activity of AB3 is attributable to improved light absorption across the entire spectrum, its large specific surface area, the separation of photo-generated electron–hole pairs, and a synergetic interaction between AVO and BWO. Additionally, the photo-stability of AB3 was greater than that of AVO. The scavenger experimental results suggested that photocatalytic RR2 degradation over AB3 was mainly governed by direct photo-generated hole oxidation. [ABSTRACT FROM AUTHOR]