Fe-Mn oxycarbide anchored on N-doped carbon for enhanced Fenton-like catalysis: Importance of high-valent metal-oxo species and singlet oxygen

A nonradical oxidation-based peroxymonosulfate (PMS) activation is an attractive process for pollutant elimination. Herein, a dual-metal-organic framework (MOF) assisted strategy to construct magnetic Fe-Mn oxycarbide anchored on N-doped carbon (FeMn@NC) was proposed for PMS activation. It was found that FeMn@NC-800 displayed superior activity than other comparable counterparts, with nearly 100 % degradation of sulfamethazine (SMZ) within 30 min. Electron paramagnetic resonance and quenching tests revealed that nonradical oxidation (1O2 and high-valent metal-oxo species) dominated the SMZ degradation process. Experimental and theoretical calculations demonstrated that FeMn oxycarbide preferred adsorbing the terminal O of PMS, which could improve the PMS oxidization to produce SO5•−, further generating 1O2. Moreover, dual active sites could lower the energy barrier to cleave the O−O bond of PMS to form high-valent FeMn＝O species. The present study provided a clue to rationally design high-performance heterogeneous catalysts and proposed a novel nonradical-based catalytic oxidation for environmental cleaning. [Display omitted] •A dual-MOFs assisted method is designed to construct FeMn@NCs for PMS activation.•1O2 and high-valent FeMn＝O species predominate in contaminant oxidation.•Both Fe-Mn oxycarbide and N-doped carbon contributes to 1O2 generation.•Synergy of Fe-Mn sites is key for formation of high-valent bimetallic-oxo species.•FeMn@NC-800/PMS system shows excellent practical applicability.