Construction of TI₃C₂ MXene–semiconductor heterostructures for efficient photocatalytic abatement of sulfamethoxazole

A series of novel MXene (Ti3C2) based photocatalysts designed to obtain an enhance photocatalytic degradation of persistent pollutants have been developed. MXene was used as co-catalyst coupled with different materials. Several materials were prepared to form heterojunctions with MXene, specifically two C₃N₄-based materials and two ZnO-based materials, a bare one and a mixed one with a very low amount of CeO₂. Sulfamethoxazole (SMZ), a widely used pharmaceutical frequently detected in aqueous systems, was selected as a model contaminant to evaluate the performance of the synthesized materials. MXene–ZnO and MXene–ZnO–CeO2 heterojunctions were synthesized and characterized to evaluate the structure, the morphology of the systems together with their optical and electronic properties. Photocatalytic tests under simulated solar irradiation showed that MXene–ZnO and MXene–ZnO–CeO2 composites were the fastest in degrading SMZ, achieving nearly complete SMZ removal within 45 min. The formation of several transformation products was assessed by LC-MS/MS, mainly associated with the S-N cleavage and hydroxylation reactions. Although SMZ was rapidly removed, toxicity prediction (ECOSAR) indicated the formation of intermediates with higher predicted toxicity, requiring longer irradiation times (around 120 min) to achieve effective detoxification.