Construction of Spatially Adjacent Ni and Co-Based Spinel Frustrated Lewis Pair Sites for Efficient Catalytic Ozonation

Abstract

Frustrated Lewis pairs (FLPs) present new opportunities for the development of highly active spinel materials for the activation of stable molecules. Herein, a Ni and Co-based spinel with abundant FLPs sites (NiCo₂O₄-F) is synthesized through morphologic defect engineering and used for efficient catalytic ozonation CH₃SH elimination. Characterization results reveal that the NiCo₂O₄-F with nanoflower structure exposes more surface oxygen vacancies (Ov), inducing local charge redistribution and forming active regions. Ov acts as Lewis basic sites, while the unsaturated coordinated Ni atoms (Ni_uc) act as Lewis acidic sites, and spatially ≈4.08 Å. The Ov···Ni_uc FLPs function as “electron shuttles” in the reaction, facilitating specific adsorption of reactants via the dual acidic–basic reaction sites, thereby activating O₃ to generate ·O₂ ⁻ and ¹O₂ species to achieve deep oxidation of CH₃SH. The resulting NiCo₂O₄-F catalyst exhibits an outstanding CH₃SH removal efficiency of 94.4%, achieving a high mass activity (5.6 ppm mg⁻¹), which is 70 times greater than that of commercial MnO₂ (0.08 ppm mg⁻¹). This work presents a promising approach to developing sophisticated ozone catalysts by controllable construction of acid–base sites on spinel surface, enhancing the understanding of the role of FLPs structure in molecular activation.