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

Abstract

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 x 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).