Mo-Fe bimetallic oxide activates peroxydisulfate for highly effective levofloxacin degradation via radical and non-radical pathways

The synergistic interaction between radical and non-radical routes in peroxydisulfate (PDS) activation over Mo-Fe bimetallic oxide remains mechanistically unclarified. Herein, a novel Fe-doped MoO₂ bimetallic oxide was rationally designed and successfully synthesized via a facile one-pot solvothermal strategy. Mo_0.85Fe_0.15O₂/PDS system achieved ~ 98% levofloxacin (LVX) removal within 20 min, which was attributed to the accelerated dual redox cycles of Fe³⁺/Fe²⁺ and Mo⁶⁺/Mo⁵⁺/Mo⁴⁺. Based on radical quenching tests, electron paramagnetic resonance, and electrochemical analyses, radical pathways (sulfate radicals (SO₄^•−), hydroxyl radicals (·OH), and superoxide radical (·O₂⁻)) and the non-radical pathway (¹O₂) worked synergistically for LVX degradation. The theoretical calculations revealed that iron doping played a vital role in enhancing interfacial electron transfer toward adsorbed PDS molecules, which facilitates the activation of the O–O bond. High-performance liquid chromatography-mass spectrometry (HPLC-MS) coupled with ecological structure–activity relationships (ECOSAR) revealed stepwise detoxification along the degradation pathways, and bean sprout assays confirmed the low toxicity of resultant intermediates. The proposed metal doping strategy enables the fabrication of high-performance Mo-based catalysts for PDS activation and sheds light on the further development of persulfate-driven remediation technologies.