Synergistic promotion effects of MoS2 integrated transition metal sulfides nanoparticles towards efficient tetracycline destruction: Performance, mechanism and toxicity assessment

Construction of effective multi-component composite materials via architecture modulation to destruct antibiotic pollutants through activating peroxymonosulfate (PMS) remains a challenge. In this study, we report a two-step hydrothermal process to construct MoS2 nanosheets integrated with transition metal sulfide (CoS2, Cu2S and MnS) nanoparticles for activating PMS towards degrading emerging tetracycline (TC) antibiotic. Among the samples, CoS2@MoS2 is verified as the best PMS activator for TC destructing with a removal rate of 95.3% in 30 min. The CoS2@MoS2/PMS system also performs well under various reaction conditions. The dominant reactive oxygen species responsible for TC degradation are identified as SO4•- and 1O2. Furthermore, CoS2@MoS2-catalyzed PMS efficiently degrades TC into eleven intermediates via three possible pathways. The toxicity of these intermediates is evaluated, both in terms of acute/chronic toxicity and phytotoxicity. The presence of Mo4+ sites on the catalyst surface facilitates the rapid transfer of electrons from MoS2 to Co3+, promotes the regeneration of Co2+, and facilitates the redox cycle of Co3+/Co2+. Therefore, the synergistic effects between CoS2 and MoS2 are responsible for the efficient degradation of TC over the CoS2@MoS2/PMS system. This study establishes an architecture engineering strategy for preparing dual transition metal sulfides, which synergistically promote PMS activation towards the degradation of organic pollutants.