Evidence for Spin Polarization and Lattice Oxygen Migration During Cyclohexane Oxidation Over CoO_x/Fe₂O₃

The selective aerobic oxidation of alkanes plays a pivotal role in the sustainable conversion of hydrocarbons. However, designing catalysts that facilitate the selective generation of radicals while avoiding side reactions (such as over-oxidation) remains a major challenge. Herein, we demonstrate the enhanced spin polarization and lattice oxygen migration on CoO_x/Fe₂O₃ catalyst for cyclohexane oxidation under solvent-free conditions. We introduce highly dispersed CoO_x clusters on iron oxide nanorods (Co/FeNR) through atomic layer deposition, forming interfacial Co–O–Fe active sites. The high-spin Co atoms modulate the spin-state of neighboring Fe atoms via double-exchange interaction, promoting the adsorption and dissociation of triplet molecular oxygen. Meanwhile, Co effectively enhances the mobility of lattice oxygen, further forming the interface-confined radical intermediate. Both spin polarization-promoted oxygen activation and lattice oxygen migration drive the transformation of interface-confined radicals, thus suppressing side reactions and enhancing selectivity. Benefiting from these effects, the 5Co/FeNR achieves 14.6% conversion and 82.7% selectivity for KA oil and mass-specific reaction rate of 830.7 mmol·g_cat⁻¹·h⁻¹, which is approximately 6 times that of FeNR. This study provides valuable insights into the rational design of efficient oxidation catalysts.