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

Abstract

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 <i>via</i> 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 <i>T</i>₉₀ (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.