Nitrogen-vacancy-rich Co3O4/carbon nitride activating peroxymonosulfate for efficient micropollutant degradation: Dominant role of superoxide radicals

The widespread use of tetracycline (TC) antibiotics poses significant environmental and health risks due to their persistence and toxicity in aquatic ecosystems. In this study, a heterogeneous catalyst composed of Co 3 O 4 supported on graphitic carbon nitride (Co 3 O 4 /CN) was developed to efficiently activate peroxymonosulfate (PMS) for TC degradation. A series of Co 3 O 4 /CN composites with different cobalt loadings were synthesized via a straightforward pyrolysis process. The optimized 12 %Co 3 O 4 /CN sample exhibited an enhanced specific surface area, abundant nitrogen vacancies, and improved electron transfer efficiency, achieving 86.6 % degradation of TC within 30 min, with 5.4-fold enhancement in reaction rate constant than PMS-only systems. Consistently high degradation efficiencies were also observed for various other micropollutants. Mechanism investigations revealed that O 2 · - radicals played a dominant role in TC degradation, while SO 4 · - , 1 O 2 , and ·OH radicals also contributed significantly, all synergistically promoted by the redox cycling of Co 2+ /Co 3+ species and the presence of nitrogen vacancies. Notably, the catalytic system exhibited broad pH adaptability, excellent reusability, and effective mineralization capacity. Toxicity assessment further indicated a reduced ecotoxicity of TC degradation byproducts. This study thus offers a promising and environmentally sustainable solution for the effective remediation of antibiotic-contaminated wastewater.