Efficient activation of peroxymonosulfate by sulfur vacancies engineered NiCo₂S₄ spheres for norfloxacin degradation

The development of efficient heterogeneous catalyst materials for the removal of antibiotic residues is crucial for safeguarding public health and environmental ecosystem. In this work, NiCo₂S₄ spheres with sulfur vacancies (NiCo₂S₄-V_S) was synthesized using hydrothermal method followed by H₂O₂ oxidation for effective norfloxacin (NOR) degradation in the presence of peroxymonosulfate (PMS). By optimizing the synthesis parameters, NiCo₂S₄-V_S-0.7 achieved an 88 % removal of NOR within 10 min through PMS activation. The NiCo₂S₄-V_S-0.7/PMS system demonstrated high NOR degradation efficiency across various water matrices and for other antibiotics, and exhibited high cycle stability. Theoretical calculations indicated that the enhanced catalytic efficiency of NiCo₂S₄-V_S was attributed to the surface sulfur vacancies, which could increase the adsorption capacity of PMS, expose sufficient active sites, and facilitate electron transfer capacity. This work highlights the significance of surface vacancy engineering in tuning PMS activation activity to enhance antibiotics elimination performance.