Photocatalytic degradation of ranitidine and reduction of nitrosamine dimethylamine formation potential over MXene–Ti3C2/MoS2 under visible light irradiation

Highlights: • MXene-Ti₃C₂/MoS₂ composites were prepared by a hydrothermal method. • A heterojunction was formed between MoS₂ and Ti₃C₂ in the composite. • The highest RAN degradation and mineralization efficiencies were 88% and 74%. • The lowest NDMA formation potential of only 2.01% was achieved. • • OH radicals contributed most to the photocatalytic activity. Photocatalysis is an effective method to degrade ranitidine (RAN), which is a typical precursor of nitrosamine dimethylamine (NDMA), an extremely potent human carcinogen. Herein, MXene-Ti₃C₂/MoS₂ composites were prepared by a hydrothermal treatment aiming to use them for the photocatalytic degradation of RAN and the reduction of NDMA formation potential (NDMA-FP) under visible light irradiation for the first time. The analysis of the morphology, chemical composition and structure of these composites as well as the results of electrochemical experiments showed that a heterojunction was formed between MoS₂ and Ti₃C₂, which facilitated the separation of electron-hole pairs and charge transfer, and thereby the photocatalytic performance. The MXene-Ti₃C₂/MoS₂ composite (MT-4) exhibited the best photocatalytic performance in 60 min, with the highest RAN degradation and mineralization efficiencies of 88.4% and 73.58%, and the lowest NDMA-FP of 2.01%. Active species, including • O₂^- radicals, h⁺ and • OH radicals, all contributed to the degradation of RAN, among which • OH radicals were the main active species involved in the photocatalytic activity. The mechanism of the photocatalytic degradation of RAN over MXene-Ti₃C₂/MoS₂ photocatalyst under visible light irradiation was proposed. This work opens up a new perspective on the applications of MXene-based materials for photocatalytic degradation of challenging pollutants.