Construction of dual Z-scheme Ag₃VO₄–BiVO₄/InVO₄ photocatalysts using vanadium source from spent catalysts for contaminated water treatment and bacterial inactivation

Vanadate-based photocatalysts have recently attracted substantial attention owing to their outstanding photocatalytic activity for degrading organic pollutants and generating energy via photocatalytic processes. However, the relatively high price of vanadium has hindered the development of vanadate-based photocatalysts for various applications. Spent catalysts obtained from oil refineries typically contain a significant quantity of vanadium, making them valuable for recovery and utilization as precursors for the production of high-value-added photocatalysts. In this study, we transformed the V present in spent catalysts produced by the petrochemical industry into ternary vanadate-based photocatalysts [BiVO4/InVO4/Ag3VO4 (BVO/IVO/AVO, respectively)] designed for water remediation. The ternary composites revealed an enhanced photocatalytic capability, which was 1.42 and 5.1 times higher than those of the binary BVO/IVO and pristine AVO due to the facilitated charge separation. The ternary photocatalysts not only effectively treated wastewater containing various organic dyes, such as methylene blue (MB), rhodamine 6G (R6G), and brilliant green (BG), but also exhibited remarkable photocatalytic performance in the degradation of antibiotics, reduction of Cr(VI), and bacterial inactivation. This paper proposes a feasible route for recycling industrial waste as a source of vanadium to produce highly efficient vanadate-based photocatalysts.