Recent advances in the development of bismuth-based materials for the photocatalytic reduction of hexavalent chromium in water

Photocatalytic reduction (PCR) is an emerging option to treat hexavalent chromium (Cr(VI)) in aquatic systems. The lamellar bismuth (Bi)-based materials are recognized as a potential platform for PCR against Cr(VI) with enhanced light harvesting ability and tunable bandgap energy. The PCR mechanism of Bi-based materials against Cr(VI) has been explored in relation to the modification strategies (e.g., heterojunction, defect engineering, and doping) and to the process variables (e.g., solution pH and the type/quantity of additives). Performance evaluation of diverse Bi-based materials has also been made using a figure of merit (FoM) as the key metric for industrially relevant conditions. Accordingly, shuriken-shaped BiVO4 with average particle sizes of 5–10 nm was recognized as the best performer with the highest FoM value (3.45 × 10–5 mol g–1 Wh–1). To scale up the utility of Bi-based materials against Cr(VI), further efforts should be directed toward drastic reduction of treatment costs for real-world applications, especially in terms of catalyst fabrication and energy consumption (due to poor quantum yield).