Enhancement of the radical pathway-dominated degradation of imidacloprid in PMS-AOP by 1T-MoS2-based dual-atom catalyst: Synergistic catalysis by Fe and Ni atoms

Abstract

Atomically dispersed heterogeneous catalysts (ADCs), represented by single-atom catalysts (SACs), have received much attention in the research of peroxymonosulfate-based advanced oxidation processes (PMS-AOPs), which has effectively solved the environmental problems caused by various emerging contaminants. However, single-atom catalysts suffer from the limitation of not being able to cope with multistep reactions using a solitary active site. This study synthesized the dual-atom catalyst FeNi_DA@1T-MoS₂ by introducing Fe and Ni atoms into 1T-MoS₂ with metallic properties, which exerted the synergistic interaction of Fe and Ni atoms while maintaining the atom-dispersed properties to enhance the spontaneity of PMS adsorption and further reduce the adsorption energy barriers of PMS at the active sites. The degradation kinetic constants of the target contaminant imidacloprid were significantly increased up to 3.6-fold by the efficient activation of PMS. Additionally, this study defines the metal contribution factor and verifies the existence of synergistic interaction between Fe and Ni atoms by comparing experimental data with theoretical values. The dominant reactive oxygen species in the degradation process were identified by quenching experiments, EPR, and probe experiments as SO₄^-· and ·OH, corresponding to a contribution of 76.72 % and 14.48 %, respectively. This work reveals the synergistic catalytic interaction of dual atoms by combining experiments with theoretical calculations and systematically elucidates the degradation mechanism of the target pollutants. This work reveals the synergistic catalytic interaction of dual-atom catalysts by combining experiments with theoretical calculations, and systematically elucidates the degradation mechanism of target pollutants. Meanwhile, it also provides a technical reference for the development of novel dual-atom catalysts and efficient emerging contaminant treatment technologies.