In-situ growth of MIL-53 (Fe) on charcoal sponge as a highly efficient and recyclable photocatalyst for removal of Cr(VI)

The application of metal–organic frameworks (MOFs) is hindered by several crucial factors, including low photocatalytic efficiency, poor stability and challenges in recycling. In this study, MIL-53(Fe) was grown in situ on a charcoal sponge (CS) with a large surface area, excellent mechanical properties, and high photocatalytic efficiency using a solvothermal method, thus addressing the above-mentioned shortcomings of MOF materials. Notably, CS/MIL-53(Fe) has an amazing light-harvesting capacity in the visible range, leading to a significant improvement in the utilization of light. The results of the experiments indicate that CS/MIL-53(Fe) displays a higher photocatalytic activity (87% Cr(VI)) when exposed to visible light than CS (58%) or MIL-53(Fe) (27%), attributing to the increased separation of photogenerated carriers. e⁻ is the main reactive radical and dominates the photocatalytic reduction process, rooting from that e⁻ can reduce Cr(VI) to low-toxicity Cr(III). This study presents a novel method for constructing photocatalysts with large surface areas, superior mechanical characteristics, and enhanced photocatalytic performance. Additionally, it achieves the resource utilization of agricultural and forestry waste.