The enhanced catalytic activity and stability of Fe 3 O 4 -S@C Fenton-like catalyst for phenol degradation

Carbon-coated Fe3O4-S (Fe3O4-S@C) Fenton-like catalyst on carbon cloth is successfully prepared by electrodeposition and subsequent ethanol solvothermal treatment. Fe3O4-S@C with amorphous Fe3O4 presents a rough network structure. Besides, the ≡Fe2+/≡Fe3+ ratio on Fe3O4-S@C is higher than that on sulfur-doped Fe3O4 (Fe3O4-S). The Fe3O4-S@C has the enhanced catalytic activity and improved cycle stability under circumneutral pH. 95.4% phenol is degraded in 18 min with 0.204 ppm of total leached iron. 95% phenol removal efficiency is still maintained after Fe3O4-S@C is reused four times, whereas the Fe3O4-S presents the sharply reduced catalytic performance after the first degradation test. The formed carbon layer not only accelerates the redox cycle of ≡Fe3+/≡Fe2+ by reducing ≡Fe3+ to ≡Fe2+ during the degradation, but inhibits the total iron dissolution effectively. Furthermore, the S6+ can form micro-acidic environment on the catalyst; thus, the degradation reaction can take place under circumneutral pH, and the Sn2− can accelerate the transformation from ≡Fe3+ to ≡Fe2+ through reduction effect. Also, the polar groups of the carbon layer can adsorb more phenol to facilitate degradation process.