Constructing Active Cu2+–O–Fe3+ Sites at the CuO–Fe3O4 Interface to Promote Activation of Surface Lattice Oxygen

Activating surface lattice oxygen (O_latt) through the modulation of metal-oxygen bond strength has proven to be an effective route for facilitating the catalytic degradation of volatile organic compounds (VOCs). Although this strategy has been implemented via the construction of the TM₁-O-TM₂ (TM represents a transition metal) structure in various reactions, the underlying principle requires exploration when using different TMs. Herein, the Cu²⁺-O-Fe³⁺ structure was created by developing CuO-Fe₃O₄ composites with enhanced interfacial effect, which exhibited superior catalytic activity to their counterparts, with T₉₀ (the temperature of toluene conversion reaching 90%) decreasing by approximately 50 °C. Structural analyses and theoretical calculations demonstrated that the active Cu²⁺-O-Fe³⁺ sites at the CuO-Fe₃O₄ interface improved low-temperature reducibility and oxygen species activity. Particularly, X-ray absorption fine structure spectroscopy revealed the contraction and expansion of Cu-O and Fe-O bonds, respectively, which were responsible for the activation of the surface O_latt. A mechanistic study revealed that toluene can be oxidized by rapid dehydrogenation of methyl assisted by the highly active surface O_latt and subsequently undergo ring-opening and deep mineralization into CO₂ following the Mars-van Krevelen mechanism. This study provided a novel strategy to explore interface-enhanced TM catalysts for efficient surface O_latt activation and VOCs abatement.