Selective hydroxyl generation for efficient pollutant degradation by electronic structure modulation at Fe sites

Hydrogen peroxide (H₂O₂) is an important green oxidant in the field of sewage treatment, and how to improve its activation efficiency and generate free radicals with stronger oxidation performance is a key issue in current research. Herein, we synthesized a Cu-doped α-Fe₂O₃ catalyst (7% Cu-Fe₂O₃) for activation of H₂O₂ under visible light for degradation of organic pollutants. The introduction of a Cu dopant changed the d-band center of Fe closer to the Fermi level, which enhanced the adsorption and activation of the Fe site for H₂O₂, and the cleavage pathway of H₂O₂ changed from heterolytic cleavage to homolytic cleavage, thereby improving the selectivity of •OH generation. In addition, Cu doping also promoted the light absorption ability of α-Fe₂O₃ and the separation of hole-electron pairs, which enhanced its photocatalytic activities. Benefiting from the high selectivity of •OH, 7% Cu-Fe₂O₃ exhibited efficient degradation activities against ciprofloxacin, the degradation rate was 3.6 times as much as that of α-Fe₂O₃, and it had good degradation efficiency for a variety of organic pollutants.