Fabrication of a carbon-coated Fe3O4 for ozone catalysis to facilitate HO2− formation during ozonation

In the O3 self-decomposition process, the poor HO2− formation efficiency limits O3 decomposition and •OH production. Although the addition of Fenton's reagent facilitates this process, H2O2 consumption and Fe(III) sedimentation must be addressed. In this study, carbon-coated Fe3O4 (Fe3O4@C) samples were prepared using the metal–organic frameworks (MOFs) modification method for the catalytic ozonation of aromatics, which effectively solved the above challenges. The fabricated 4-Fe3O4@C catalyst not only exhibited a yolk-shell structure, but also increased •OH production by 9-fold, resulting in optimal target removal, mineralization, and O3 decomposition efficiency. Further investigation confirmed that the activity of 4-Fe3O4@C was owing to the combined action of Fe(II) on the catalyst surface and the H2O2 produced from aromatic degradation. Furthermore, the outer carbon layer with reducing properties regenerated Fe(II) in a timely manner, ensuring catalyst durability. Finally, a clear pathway for enhancing O3 decomposition and •OH generation is proposed.