Transition metal vanadates (MVO; M=Bi, Fe, Zn) synthesized by a hydrothermal method for efficient photocatalysis

Metal vanadates (MVO) have attained a lot of consideration in recent years because of their unique structural and photoluminescence features. These metal vanadates adopt structures with different phases depending on the magnitude of the bivalent present. Here, the hydrothermal approach was used to synthesize three different phases of MVO (M=Bi, Fe, and Zn). After synthesis temperatures of 200 °C for 24 h, powders of BiVO 4 (monoclinic), FeVO 4 (anorthic), and ZnV 2 O 4 (cubic) were produced. Scherrer’s evaluation confirmed that these crystallites were nanosized. According to BET data, ZnV 2 O 4 has a sufficient surface area. The bandgap transition of metal vanadates is of the order of FeVO 4 < BiVO 4 < ZnV 2 O 4 based on UV–Vis spectra. These MVO have interesting optical properties, and photoluminescence (PL) analysis revealed blue-green emission peaks in PL spectra and other obtained results exposed that crystallinity, shape, and size of the metal vanadates have a significant impact on the photocatalytic activity. The photocatalytic degradation of crystal violet (C 25 H 30 ClN 3 l) dye over these hydrothermally synthesized MVO was investigated. In this research, ZnV 2 O 4 spinel oxide offered the best photodegradation efficiency of crystal violet at 99.92% within 60 min under visible light irradiation. The photocatalytic mechanism of this MVO was postulated and carefully reviewed.