Confined Cobalt in Hierarchical Boron/Nitrogen-Modified Carbon for Fenton-like Norfloxacin Degradation via Peroxymonosulfate Activation.

Peroxymonosulfate activation provides a powerful route for degrading persistent antibiotics, yet cobalt-based catalysts face an activity-stability dilemma. Exposed Co sites promote oxidant activation, whereas solution-accessible Co species can dissolve during PMS activation. Here we address this challenge by confining Co nanoparticles within a polarized B/N-modified carbon interface in a hierarchical MOF-derived catalyst. The optimized 10Co@BCN is prepared through liquid-phase self-assembly of bimetallic MOF nanofibers followed by gas-solid B/N codeposition, yielding carbon-encapsulated Co nanoparticles embedded in a B/N-modified carbon matrix and organized into nanofiber-assembled microspheres. In PMS-mediated norfloxacin degradation, 10Co@BCN achieves 98.3% NFX removal within 25 min and maintains high removal activity over five cycles. Efficient end point removal is also observed in the tested inorganic-ions, real-water matrices, and several organic pollutants. Relative to Co@C, wet-impregnated Co/BCN, and bare Co nanoparticles, the in situ-formed Co-BCN architecture markedly improves Co retention. Concentration-dependent quenching, EPR spectra, and electrochemical response collectively support a tentative coupled oxidation network involving SO4•-/•OH radical oxidation, O2•-/1O2 associated pathways, and interfacial electron transfer. DFT calculations further indicate that B/N comodification enhances interfacial charge redistribution and thermodynamically favors PMS adsorption on the interface. TOC and LC-MS analyses suggest substantial mineralization and progressive molecular cleavage of NFX into residual transformation products. This work demonstrates a confinement-interface strategy that couples improved Co retention, hierarchical mass transport, and electronically regulated PMS activation in MOF-derived catalysts.