Solvent-free mechanochemical preparation of Fe-N-C loaded MnO2 to efficiently activate peroxymonosulfate for norfloxacin degradation

Fe- and nitrogen-doped carbonaceous (Fe-N-C) sites supported on MnO 2 (Fe-N-C@MnO 2 ) were prepared by a solvent-free mechanochemical method for peroxymonosulfate (PMS) activation to degrade norfloxacin (NFX). After a 50-min ball milling of iron(II) phthalocyanine (Fe( II )Pc) and MnO 2 at a weight ratio of 7.5 %, the obtained Fe-N-C@MnO 2 exhibited exceptional activity in PMS activation, achieving nearly complete degradation of NFX in 5 min with a rate constant of 0.62 min −1 . This rate constant was 11.5 and 28.2 times higher than that for milled MnO 2 (bm-MnO 2 ) and the mixture of Fe( II )Pc and MnO 2 , respectively. Alternative iron sources (FeSO 4 , FeCl 2 , Fe(III)-EDTA) and phthalocyanine showed no enhancement. Characterization revealed Fe-N-C@MnO 2 possessed abundant Mn 3+ , oxygen vacancies and Fe-N-C sites. Combined experimental and computational studies demonstrated Fe-N-C@MnO 2 simultaneously enhanced the 1 O 2 generation and facilitated the formation of SO 4 •− , •OH and O 2 •− , with contributions to NFX degradation following: 1 O 2  > •OH ≈ O 2 •−  > SO 4 •− . This work establishes mechanochemical coordination engineering as a facile strategy for constructing high-performance metal-N-C hybrid catalysts.