Efficient activation of peroxymonosulfate by Mo₂TiC₂T_x@Co for sustained emerging micropollutant removal: Mo vacancy-mediated activation in Fenton-like reactions

Developing advanced heterogeneous catalysts through structural modifications effectively enhances the catalytic activity of non-homogeneous catalysts for removing emerging micropollutants (EMPs). In this study, Mo₂TiC₂T_x@Co with Mo vacancies was synthesized using the Lewis molten salt method, which efficiently activates peroxymonosulfate (PMS) and continuously degrades EMPs in water. The abundant Mo vacancy structure in the material acts as an anchoring site for Co nanoparticles and a co-catalytic site for Fenton-like reactions, enabling PMS adsorption and activation. Furthermore, Mo facilitates the redox cycling of Co³⁺/Co²⁺ through electron transfer. Mo vacancy-mediated activation in Fenton-like reactions enabled the Mo₂TiC₂T_x@Co/PMS system to achieve superior degradation efficiency for sulfamethoxazole (SMX) and several other EMPs, with the SMX degradation rate being 52.7 times higher than that of the Mo₂TiAlC₂/PMS system. The system exhibited robust resistance to various anionic species and maintained high activity over a wide pH range. The Mo₂TiC₂T_x@Co /PMS system degrades EMPs in water through both free radical (SO₄^•- and •OH) and non-radical (¹O₂) mechanisms, enhancing EMPs removal from complex water environments. This study aims to develop an efficient and sustainable heterogeneous catalyst, offering a viable solution for the long-term and effective degradation of EMPs in water.