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-Co 3 O 4 co-catalyst enriched with oxygen vacancies (O v ) 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 Co 3 O 4 crystal, generating large amounts of O v , 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 of the NF/MXene-Co 3 O 4 /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-Co 3 O 4 . 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.