Photoinduced acceleration of Fe3+/Fe2+ cycle in heterogeneous FeNi-MOFs to boost peroxodisulfate activation for organic pollutant degradation

Abstract

The sluggish regeneration rate of Fe²⁺ in Fe-based heterogeneous catalysts restricts their wider application in persulfate-based advanced oxidation process (PS-AOPs). To conquer such challenge, Fe-embedded Ni-based metal-organic frameworks (FeNi-MOFs) with heteroatomic metal nodes were prepared and employed for persulfate activation to construct highly efficient PS-AOPs. Spectral analyses and density functional theory (DFT) calculations elucidated that the ligand-to-metal charge transfer and polarization of adjacent Ni centers endowed accelerated Fe³⁺/Fe²⁺ redox cycle in the resultant FeNi-MOFs under light irradiation and thus promoted the Fe²⁺ recovery with Fe³⁺/Fe²⁺ cycling efficiency > 58%. Consequently, the FeNi-MOFs delivered remarkable performance in peroxodisulfate activation and higher specific activity than that of the control Ni-MOFs/Fe³⁺ and state-of-the-art catalysts reported to date. This study provides new avenue of the accelerating Fe³⁺/Fe²⁺ circulation in entirely heterogeneous systems for persulfate activation and also highlights the great potential of MOFs in design of high-performance Fe-based catalysts for PS-AOPs.