Sustainable waste-derived heterojunction photocatalysts for multifunctional environmental application

This study aimed to develop a sustainable and recyclable method for synthesizing MIL-101(Fe) using organic linkers derived from waste poly (ethylene terephthalate) (PET), contributing to the valorization of plastic waste. The PET-derived MIL-101(Fe) was further modified by anchoring CuS nanoparticles onto its surface, resulting in CuS@MIL-101(Fe) heterojunction photocatalysts with varying CuS loadings (10-50 wt%). Characterization results indicated the successful incorporation and homogeneous distribution of CuS nanoparticles within the MIL-101(Fe) framework, accompanied by strong interfacial interactions, without significant alteration of the parent MOF structure. Optical analyses revealed enhanced visible-light absorption and reduced electron-hole recombination for the heterojunctions compared to pristine MIL-101(Fe). We evaluated the photocatalytic performance under visible-light irradiation through the degradation of rhodamine B and the photocatalytic oxidative desulfurization of sulfur-containing compounds. Among the prepared catalysts, 30 wt% CuS@MIL-101(Fe) demonstrated the highest activity, achieving 99.7% dye degradation and 95.6% sulfur removal. The introduction of an external oxidant significantly promoted the generation of reactive oxygen species, further enhancing photocatalytic efficiency. However, excessive CuS loading led to particle aggregation, which reduced photocatalytic performance. Overall, this work demonstrates that integrating waste-derived MOFs with advanced oxidation processes can lead to the development of high-performance, environmentally friendly photocatalysts, offering a promising pathway for sustainable environmental remediation applications.