Insight into the Enhanced Photo-Fenton Degradation Performance of Fe3O4@β-Ketoenamine-Linked Covalent Organic Framework

The sluggish charge-transfer kinetics of Fe(II) regeneration, unsatisfactory utilization of H2O2, and low reaction efficiency remain largely unresolved in Fe3O4-based heterogeneous photo-Fenton systems. Herein, an in situ covalent attaching strategy was employed to fabricate Fe3O4@covalent organic framework (COF) core–shell heterostructures. By virtue of this, enhanced photoresponsive behavior was obtained to tailor the regeneration kinetics for Fe(II) and ideal catalytic sites for H2O2 were provided. Molecular engineering was further employed to manipulate the linkages (β-ketoenamine or imine) of the COFs. Bearing a β-ketoenamine linkage, the Fe3O4@TpTta COF exhibited remarkably fast kinetics (0.111 min–1) as well as exceptional pH tolerance in photo-Fenton degradation of methylene blue, which stands out among the state-of-the-art photocatalysts. Combined with theoretical calculations, the electron-transfer route and interfacial interactions between the oxidant and catalysts with different linkages were fully revealed, giving insight into the synergistic relationship between photocatalysis and Fenton reactions.