Spinel lattice distortion and oxygen vacancy dynamics in self-standing NiCo2-xFexO4: mechanistic investigation of peroxymonosulfate activation pathways for antibiotic degradation.

The development of recoverable catalysts for advanced oxidation processes remains a critical challenge in environmental remediation. This study addresses the limitations of powder catalysts through the hydrothermal calcination synthesis of Fe doping NiCo2O4 spinel oxide nanosheets anchored on three-dimensional porous nickel foam, establishing a novel heterogeneous catalytic system for peroxymonosulfate (PMS) activation. The NiCo1.8Fe0.2O4/NF + PMS system achieved 92.3 % ± 1.2 % degradation of levofloxacin within 30 min, driven by synergistic radical and non-radical mechanisms dominated by singlet oxygen generation. Systematic characterization revealed oxygen vacancies as pivotal active sites for PMS adsorption and activation, with lattice oxygen-mediated dynamic reconstruction maintaining vacancy stability during cycles. The catalyst exhibited exceptional performance across pH 3-9 and demonstrated resistance to common anionic interferents, while 6-cycle experiments retained 86.8 % ± 0.8 % initial activity. Notably, the integration of a continuous-flow fixed-bed reactor enabled long-term degradation of levofloxacin without centrifugal separation, highlighting the material's engineering scalability. This work advances advanced oxidation processes by elucidating the correlation between spinel lattice distortion and non-radical pathway efficiency, offering a recoverable catalyst framework with broad applicability for refractory pollutant removal.