Electronic modulation of fiber-shaped-CoFe2O4 via Mg doping for improved PMS activation and sustainable degradation of organic pollutants

Advanced oxidation processes (AOPs) driven by transition metal oxides are promising systems for the removal of organic pollutants. However, the catalytic activity is still limited by the low redox property of the active site. In this study, a novel and robust fiber-shaped cobalt ferrite catalyst was synthesized through a magnesium doping strategy. Detailed structural characterization and theoretical calculations demonstrated that the doping of Mg into CoFe2O4 maintains the spinel structure but increased the electron density of Co sites due to its similar atomic radius but different electronegativity to Co. Remarkably, the optimized MCFO-0.4 achieved superior capability for peroxymonosulfate (PMS) activation and outstanding performance for the catalytic degradation of Ponceau 2R (PR). Furthermore, the inherent crystal stability and magnetic nature of spinel allows for magnetically reusability and ultra-low cobalt leaching of MCFO-0.4. Radical quenching and EPR results confirmed the involvement of singlet oxygen and hydroxyl radicals during PMS activation, and a possible catalytic mechanism was finally proposed. This work provides a case study on microstructural regulation and electron modulation in spinel catalysts, which may provide now clues to further improve the activity of oxidation catalysts for large-scale wastewater treatment.