Boosting Peroxymonosulfate Activation via CoS/MXene Nanocomposite for Rhodamine B Degradation under Simulated Sunlight Irradiation

Cobalt-based heterogeneous catalysts have been demonstrated as an effective PMS activator for pollutant degradation. However, the limited active sites on their surface lead to an unsatisfactory catalytic efficiency. Immobilizing the catalysts on the support material can be a promising modification strategy to solve this problem. MXene has been considered as an ideal support material due to its unique morphology and physicochemical properties. Therefore, in this work, the CoS-loaded Ti3C2 MXene (CoS/Ti3C2 MXene) catalyst for peroxymonosulfate (PMS) activation was successfully synthesized through a solvothermal method. Under the simulated sunlight irradiation, the CoS/Ti3C2 MXene+PMS system achieved an impressive efficiency in removing the organic pollutant rhodamine B (97.2 % in 10 min). Among the tested catalysts, 30 %-CoS-TC stood out, exhibited a broad pH tolerance from 5 to 9 and maintained robust degradation performance over cycles. Upon detailed analysis, the degradation mechanism revealed the collaborative action dominated by singlet oxygen, and supplemented by photogenerated holes and superoxide radicals in the process. Notably, the sandwich-like structure of MXene played a pivotal role, not only dispersing the CoS particles evenly on the surface of catalysts, but also providing ample space for the active sites, thus accelerating the PMS activation for the degradation of rhodamine B. Overall, this study developed an innovative MXene-based catalyst for the application of environmental remediation. Three pathways worked collectively during the degradation process of photo-Fenton-like catalysts. Particularly, rhodamine B degradation was primarily attributed to 1O2 (singlet oxygen), which was generated along with the redox cycle of Co3+/Co2+.The process was also supplemented by photogenerated holes and & sdot;O2- (superoxide radicals). The structure of MXene offered ample space for accommodating functional nanomaterials, thus accelerating the PMS activation process.+image