Rational Design of CeO2/CdSe Heterojunction Photocatalysts toward Enhanced Charge Separation for Efficient Photoreduction of Cr(VI) and Photodegradation of Tetracycline Hydrochloride

The rapid development of modern industry has exacerbated water pollution, posing significant threats to environmental sustainability and human health. Semiconductor heterostructures have emerged as a promising strategy to enhance the photochemical properties and catalytic activity of heterogeneous catalysts, offering a viable solution to water pollution challenges. In this study, a series of CeO₂/CdSe catalysts was successfully synthesized via chemical deposition. The results demonstrate that CdSe nanoparticles could effectively modulate the band gap, enhance visible light absorption ability, and improve the photochemical performance of CeO₂/CdSe composites. The catalytic activity and practical application prospects of the as-synthesized samples were evaluated by reducing hexavalent chromium (Cr(VI)) and decomposing tetracycline hydrochloride (TCH). CeO₂/CdSe composites exhibited significantly higher photocatalytic activities compared to pure CdSe and CeO₂. Notably, CeO₂/0.6CdSe demonstrated the highest photocatalytic activity, achieving 93.6% removal of Cr(VI), which was 4.39 and 1.77 times as high as those of pure CeO₂ and CdSe in sequence. Furthermore, CeO₂/0.6CdSe achieved a remarkable TCH removal rate of 97.0%. The enhanced photocatalytic performance of CeO₂/0.6CdSe is attributed to the formation of heterojunction structures between CdSe and CeO₂, which facilitates efficient charge separation and transfer. Cyclic experiments confirmed the excellent anti-interference ability and sustainability of CeO₂/0.6CdSe. Reduction mechanisms of Cr(VI) and degradation mechanisms of TCH were thoroughly investigated, with DFT mechanistic analysis providing further insights into the superior catalytic activity of CeO₂/0.6CdSe. This work highlights the potential of CeO₂/0.6CdSe as a highly efficient photocatalyst with broad applications in wastewater treatment.