Regulating 4f-2p-3d Orbital Coupling in CeO₂ via Dual-Transition Metal Doping for Efficient Peroxymonosulfate...

Peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) face persistent kinetic limitations in CeO₂ catalysts, notably sluggish interfacial electron transfer and inefficient desorption of oxygen-containing intermediates. Herein, we engineered a dual- transition-metal (Fe/Co)-doped CeO₂ catalyst via self-templating synthesis, establishing a gradient 4f-2p-3d orbital coupling unit to optimize electronic structures. Comprehensive characterization revealed that Fe/Co co-doping induced lattice distortions, elevated Ce (IV) content, narrowed the 3d (Fe/Co)-2p (O) energy gap, and enhanced interfacial electron transfer at 4f (Ce) sites. The optimized FeCo3-CeO₂ exhibited superior PMS activation efficiency, achieving a norfloxacin degradation rate constant (k_obs) of 0.2539 min^-1, outperforming Fe-CeO₂ and Co-CeO₂ by 25-fold and 7-fold, respectively. Mechanistic studies confirmed dual radical/non-radical pathways, where Ce sites drove ¹O₂ generation while Fe/Co sites initiated SO₄ ^•- formation. DFT calculations demonstrated a significant reduction in PMS-intermediates desorption energy (14.70→12.49 eV), effectively resolving kinetic bottlenecks. The catalyst demonstrated broad pollutant applicability, robustness across diverse water matrices, and sustained > 99% pollutant removal during 12-h continuous-flow operation. This work provides foundational insights for designing of high-efficiency 4f-material catalysts via precise regulation 4f-2p-3d orbital coupling for water purification.