Efficient visible-light-driven photocatalytic degradation of antibiotics in water by MXene-derived TiO2-supported SiO2/Ti3C2 composites: Optimisation, mechanism and toxicity evaluation

Photocatalytic technology has emerged as a promising solution to global water contamination, mainly through the effective degradation of persistent pharmaceutical pollutants. However, a few challenges still exist in enhancing degradation efficiency, reducing the toxicity of by-products, and ensuring cost-effective scalability. This study focuses on Tetracycline Hydrochloride (TCH) as an index antibiotic pollutant to evaluate the performance of a novel MXene-derived TiO₂-supported SiO₂/Ti₃C₂ composite (SMXT) synthesized using ultrasonic and wet impregnation techniques. The SMXT-450 sample, annealed at 450 °C, exhibited a remarkable 95% degradation of TCH within 80 min, surpassing more complex three-component systems. The superior photocatalytic activities, validated through comprehensive characterisation tests, were found to stem from an optimized band gap, minimised electron-hole recombination, and enhanced charge transfer. The effective degradation process, primarily driven by •O₂⁻ and •OH radicals, was confirmed by trapping and ESR analysis. High-performance liquid chromatography (HPLC) and toxicity assessments also revealed that the intermediate degradation products are less harmful, further demonstrating the environmental sustainability of the formulated nanocomposites in treating antibiotic-polluted waters. This study's findings can highlight the potential of MXene-derived nanocomposites for the efficient remediation of antibiotic-contaminated water, offering a cost-effective and scalable approach to mitigating the impact of pharmaceutical pollutants on aquatic ecosystems.