Peroxymonosulfate Activation by Oxygen Vacancies-Enriched Mxene Nano-Co3o4 Co-Catalyst for Efficient Degradation of Refractory Organic Matter : Efficiency, Mechanism, and Stability

Cobalt-based catalysts have been widely explored in the degradation of organic pollutants based on peroxymonosulfate (PMS) activation. Herein, we report an MXene nano-Co3O4 co-catalyst enriched with oxygen vacancies (Ov) and steadily fixed in nickel foam (NF) plates, which is used as an efficient and stable PMS activator for the removal of 1,4-dioxane (1,4-D). Ti originating from MXene was doped into the Co3O4 crystal, generating large amounts of Ov, which could provide more active sites to enhance PMS activation and facilitate the transformation of Co 2+ and Co 3+ , causing a high stability. As a result, the 1,4-D removal efficiency of the NF/MXene-Co 3 O 4 /PMS system ( k app : 2.41 min -1 ) was about four times higher than that of the NF/Co 3 O 4 /PMS system ( k app : 0.62 min -1 ). In addition, singlet oxygen was the predominant reactive oxygen species. Notably, the 1,4-D removal rate of the NF/MXene-Co3O4/PMS system was over 95% after 20 h operation in the single-pass filtration mode with only 3.72% accumulative Co leaching, showing excellent stability and reusability of NF/MXene-Co3O4. This work provides a defect engineering strategy to design a robust and stable catalytic system for water treatment, which expands the application of MXene in the field of environmental remediation