Metal Defect Engineering in Spinel Oxides for Efficient Benzene Catalytic Oxidation: Divergent Electronic Configuration Modulation Mechanisms of Mn versus Co Defects

Abstract

Metal defect engineering can act as an effective strategy to adjust the electronic structure and optimize active sites for VOCs catalytic oxidation, whereas relatively high energy barriers hinder the controlled formation of metal defects in the catalysts. Herein, Mn/Co defective CoMn spinel was synthesized to elucidate the influence of metal defect types on the performance and reaction mechanism. The Mn/Co defects preferentially occupied tetrahedral coordination environments in the spinel, with Mn defects exhibiting superior activity over Co defects for benzene catalytic oxidation. The introduction of Mn defects facilitated oxygen vacancy formation and elongated Mn/Co−O bond strength, promoting the generation of reactive oxygen species. Mn defect-mediated electron delocalization induced upward shifts in the d-band center of Co/Mn, leading to a higher electron density near the Fermi level. The charge redistribution enabled more efficient interfacial electron transfer, resulting in enhanced benzene/O2 adsorption and an improvement in the reaction rate. Moreover, the high correlation between the catalytic activity and Co3+ content/Co−O covalency confirmed that the Co species might dominate the Co−Mn synergy in the boosted benzene combustion.