Hierarchical Multi-Active N-Doped Yolk-Shell Wrapped Co3O4 Nanoreactors as Highly Active Peroxymonosulfate Activator for Tetracycline Degradation

Advanced oxidation processes (AOPs) have attracted extensive attention at home and abroad as an emerging pollution control method based on sulfate radicals. Designing hollow nanoreactors with hierarchical interiors can greatly improve catalytic efficiency and show promising potential for the degradation of organic pollutants. In this paper, a novel N-doped yolk-shell wrapped Co₃O₄ (NYS Co₃O₄) nanoreactor was synthesized. Thanks to its outstanding structural features and unique spatial confinement effect, the as-prepared NYS Co₃O₄ nanoreactor demonstrated high efficiency in activating PMS, achieving 99.6% removal of tetracycline (TC) within 45 min. The influence of reaction parameters (pH value, co-existing ions, etc.) on the degradation of TC was systematically studied. Competitive radical scavenging tests revealed the primary role of h⁺ in TC removal. The HPLC-MS is used to identify the substances between the degradation of TC and suggest possible degradation pathways. The toxicities of the intermediate products were also analyzed. This work highlights that yolk-shell structured catalysts have broad application prospects in AOPs.