Photoinduced Acceleration of Fe3+/Fe2+ Cycle in Heterogeneous Feni-Mofs to Boost Peroxodisulfate Activation for Organic Pollutant Degradation

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.