Interfacial oxygen vacancy-metal dual-sites on NiFe2O4/Ni@NC dictating dominant singlet oxygen evolution from peroxymonosulfate activation

Herein, we identified interfacial oxygen vacancy-metal (O V -Ni) dual-sites within a NiFe 2 O 4 /Ni@NC composite as the definitive structural origin for dictating the selective evolution of singlet oxygen ( 1 O 2 ) from peroxymonosulfate (PMS) activation. The catalyst was fabricated via in-situ pyrolysis of a Ni-MOF on NiFe 2 O 4 nanoparticles, and its mechanism was elucidated through a combination of in-situ spectroscopy, kinetic analysis, and density functional theory (DFT) calculations. This 1 O 2 -driven catalysis achieved an 11-fold enhancement in the levofloxacin degradation rate, with the interfacial synergy lowering the non-radical pathway’s energy barrier by 0.037 eV. We conclude that these engineered dual-sites deterministically control reaction selectivity, as proven by the first experimental trapping of a surface-bound 1 O 2 precursor. This work establishes a design blueprint for advanced non-radical catalysts by transforming the approach from serendipitous discovery to predictable, interface-driven design.