Surface functionalized treatment of Co3O4 by modifying phosphate group to boost peroxymonosulfate activation for effective degradation of antibiotic

To address the limitations of poor dispersion, slow charge transfer, and insufficient stability of Co-based catalysts in peroxymonosulfate (PMS) activation for antibiotic degradation, we innovatively modified Co 3 O 4 surface with phosphate group. Subsequently, the catalytic performance of the modified catalyst (denoted as P-Co 3 O 4 -2) for PMS activation for sulfamethoxazole degradation was systematically explored. Interestingly, the phosphate group modification can significantly enrich surface hydroxyl groups and oxygen vacancies on Co 3 O 4 . The increased hydroxyl groups can promote the hydrophilicity and aqueous dispersion of P-Co 3 O 4 -2, while the enhanced oxygen vacancies can accelerate metal valence cycle and interfacial charge transfer. As a result, the P-Co 3 O 4 -2 can effectively activate PMS to generate free radicals (SO 4 •– and •OH) and high-valent metal-oxo species (Co 4+ =O). In the P-Co 3 O 4 -2/PMS system, the highest removal efficiency of sulfamethoxazole was as high as 96.4% within 16 min, and possible pathway of sulfamethoxazole degradation was also studied. Additionally, surface-bound phosphate group acted as a protective layer, suppressing Co leaching and improving catalytic stability. In short, this work provided a novel and effective surface modification strategy for cobalt-based catalysts, offering a promising approach for the remediation of antibiotic-contaminated wastewater.