Facile Synthesis of Co₃N Nanosheets for Effective Antibiotic Degradation via Peroxymonosulfate Activation

Persistent antibiotic contamination in aquatic environments poses serious threats to ecosystems and human health, necessitating the development of efficient heterogeneous catalysts for advanced oxidation processes. Herein, we report the facile synthesis of ultrathin Co₃N nanosheets (Co₃N NS) via a two-step method involving the controlled precipitation of Co(OH)₂ nanosheets followed by thermal nitridation under NH₃ atmosphere at 350 °C. The resulting Co₃N NS exhibits a well-defined two-dimensional morphology with abundant Co-N active sites, high specific surface area, and strong electron-donating capability, rendering it an exceptional activator for peroxymonosulfate (PMS). In the Co₃N NS/PMS system, norfloxacin (NOR), a representative fluoroquinolone antibiotic, was almost completely degraded within 30 min under optimal conditions ([Co₃N NS] = 0.3 g L⁻¹, [PMS] = 1.0 mM, pH 7.0). Mechanistic investigations combining quenching experiments, electron paramagnetic resonance (EPR) spectroscopy, isotope-labeling (H₂O/D₂O), and in situ Raman spectroscopy revealed that singlet oxygen (¹O₂) and high-valent cobalt-oxo (Co(IV)=O) species are the dominant reactive species via a predominantly non-radical pathway. The catalyst demonstrated remarkable stability over five consecutive cycles with negligible performance decline and effectively degraded diverse antibiotics and other organic pollutants in complex water matrices. This work provides a conceptually straightforward strategy for designing transition metal nitride catalysts for water decontamination applications.