Surface functionalized treatment of Co₃O₄ by modifying phosphate group to boost peroxymonosulfate activation for...

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 Co₃O₄ surface with phosphate group. Subsequently, the catalytic performance of the modified catalyst (denoted as P-Co₃O₄-2) for PMS activation for sulfamethoxazole degradation was systematically explored. Interestingly, the phosphate group modification can significantly enrich surface hydroxyl groups and oxygen vacancies on Co₃O₄. The increased hydroxyl groups can promote the hydrophilicity and aqueous dispersion of P-Co₃O₄-2, while the enhanced oxygen vacancies can accelerate metal valence cycle and interfacial charge transfer. As a result, the P-Co₃O₄-2 can effectively activate PMS to generate free radicals (SO₄^•- and •OH) and high-valent metal-oxo species (Co⁴⁺=O). In the P-Co₃O₄-2/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.