Enhanced PMS activation through CuMo2S3 chalcogenide: Crucial role of MoXSX in restoring the Cu active sites of catalyst for pollutants removal

Copper-based heterogeneous catalysts are highly attractive for advanced oxidation processes, but their effectiveness in wastewater treatment is limited due to the slow regeneration of Cu+ active sites. To solve this issue, we developed a dual-center binary metal chalcogenide (CuMo2S3) catalyst where the electron-rich MoXSX sites consistently reduce Cu2+ sites at the catalyst surface via feasible electron transfer reactions, ensuring efficient peroxymonosulfate (PMS) activation. The results demonstrate that the CuMo2S3 catalyst was 5-14 folds more reactive than various control and traditional co-catalytic systems. The CuMo2S3 + PMS system demonstrated a significantly higher tetracycline (TC) degradation rate (kobs) of 0.053 min-1, outperforming Cu2+/MoS2 + PMS (kobs = 0.012 min-1), MoS2 + PMS (kobs = 0.007 min-1), CuS + PMS (kobs = 0.022 min-1), CuO + PMS (kobs = 0.008 min-1), CuMoO4 + PMS (kobs = 0.023 min-1), and Cu2+/WS2 + PMS (kobs = 0.004 min-1) systems. Additionally, the CuMo2S3 + PMS system exhibited consistency under a broad pH range (3.0-11.0), excellent efficiency and stability in treating real water samples, and minimal interference from background electrolytes or organic matter. The degradation pathway of TC and PMS activation, involving multi-reactive species (SO4 center dot-, center dot OH, center dot O2-, 1O2) and electron transfer, was proposed based on chemical scavengers, electron paramagnetic resonance (EPR), XPS, electrochemical, and liquid chromatography coupled with mass spectrometry (LC-MS) analysis. This study highlights the key role of electron-rich MoXSX sites in the regeneration of Cu+ ions, demonstrating that the binary CuMo2S3 chalcogenide is an efficient Fenton-like catalyst for oxidative removal of organic pollutants.