MOF-Derived Hollow CoFe@NC Nanocages for Highly Efficient Degradation of Textile Fibers

The accelerated accumulation of synthetic textile fibers, particularly 100% polyester (PET), poses a persistent environmental challenge due to their chemical inertness and resistance to degradation. Herein, hollow CoFe@NC nanocages were synthesized through a cyanometalate-assisted transformation of ZIF-67 nanocubes followed by reductive calcination, producing metallic CoFe alloy domains confined within an N-doped graphitic carbon framework. The optimized CoFe@NC-600 catalyst exhibited a hollow architecture, abundant accessible active sites, and strong metal-carbon interfacial coupling for efficient peroxymonosulfate (PMS) activation. Under visible-light irradiation, the CoFe@NC-600/PMS system achieved 99.2% degradation efficiency toward real PET textile substrates, confirmed by gravimetric analysis, total organic carbon (TOC) measurement, and degradation product identification. Beyond conventional semiconductor photocatalysis, this work demonstrates that metallic alloy-carbon interfaces can efficiently utilize visible light through coupled photothermal conversion, interfacial electronic activation and CoFe redox mediation to drive PMS oxidation. X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), radical quenching experiments and density functional theory (DFT) calculations reveal that the CoFe/N-doped carbon interface facilitates PMS adsorption, electron transfer and O─O bond activation, promoting the generation of radical and nonradical reactive species. This study provides new insights into metal-carbon hybrid catalysts for advanced oxidation processes and offers a sustainable approach for the remediation of persistent polymer wastes.