Sulfur-doped CoFe2O4 as an efficient peroxymonosulfate-activated catalyst for carbamazepine removal: The key role of sulfur and mechanism study

Herein, sulfur-doped CoFe 2 O 4 (S-CoFe 2 O 4 ) has been developed as a highly efficient peroxymonosulfate (PMS) activator for the degradation of carbamazepine (CBZ), a persistent pharmaceutical pollutant. The incorporation of sulfur significantly enhances the catalytic performance of CoFe 2 O 4 . Under optimal conditions, almost complete removal of CBZ can be achieved within 20 min. Characterization techniques, such as X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), and electrochemical experiments, reveal that the incorporation of sulfur modifies the electronic structure of CoFe 2 O 4 . It reduces the electron transfer resistance and promotes the generation of reactive oxygen species (ROSs). Density functional theory (DFT) calculations confirm that sulfur doping increases the charge density of Co-S and Fe-S bonds, leading to the formation of low-valent Fe and Co species in S-CoFe 2 O 4 , which in turn lowers the energy barrier for ROSs formation and thereby facilitates the adsorption and activation of PMS. Moreover, the S-CoFe 2 O 4 catalyst demonstrates excellent stability and reusability, maintaining high efficiency over multiple cycles. This study highlights the crucial role of sulfur in enhancing PMS activity and offers valuable insights into the design of efficient metal-based catalysts for advanced oxidation processes in water treatment.