Enhancing Photocatalytic Cr(VI) Detoxification and N2 Fixation through Construction of a Z-Scheme Heterojunction via Partial Derivatization of BiOBr on the MOF-808/Bi-BDC Composite

The ever-increasing demand for sustainable and renewable energy sources has prompted researchers to explore promising technologies that can convert light energy into useful forms. Among these technologies, photocatalysis is gaining importance. Bismuth-based metal–organic frameworks (MOFs) possess a unique structure that facilitates efficient separation and transfer of charge carriers, making them a viable option for photocatalytic applications. In this study, we aimed to enhance the photocatalytic activity of Bi-BDC by synthesizing a composite structure of MOF-808/Bi-BDC and partially derivatizing Bi-BDC to create BiOBr, which enhances visible light absorption. The resulting photocatalyst demonstrated excellent performance, reducing a 10 ppm Cr(VI) solution at pH = 2 in just 75 min, outperforming any individual component of the composite. Additionally, the photocatalytic nitrogen fixation reaction produced a green ammonia production rate of 189.5 μmol/g–1·h–1, indicating a highly effective catalyst performance under specific test conditions. Incorporating MOF-808 in the creation of the Z-scheme heterojunction played a crucial role in suppressing charge recombination. The findings suggest that MOF-808/Bi-BDC/BiOBr is an environmentally friendly and cost-effective photocatalyst with the potential to address challenges related to sustainable ammonia production, as well as for removing toxic Cr(VI) from water. The newly created catalyst shows significant potential for utilization across various applications.