Unraveling the High Catalytic Performance of Three-Dimensional Urchin-like CoNi/NF for Toluene Oxidation: Role of Microstructure and Redox Properties

This study reports the in situ synthesis of three-dimensional (3D) urchin-like CoNi/NF composite catalysts on nickel foam (NF) via a hydrothermal method, specifically targeting toluene oxidation. The catalyst demonstrates remarkable catalytic oxidation activity, cyclic stability, and water resistance, with a T₉₀ (the temperature at which the toluene conversion rate reaches 90%) of 266 °C. The results revealed that the interconnected porous nickel foam structure facilitated the growth of metal oxides on its surface. Furthermore, the interaction among the components promoted the formation of a perfect hollow urchin-like structure, effectively mitigating particle aggregation and resulting in a large specific surface area. This morphology favored the exposure of numerous active sites, enhancing toluene adsorption and activation. Additionally, the synergistic effect between Co and Ni results in the formation of Ni-O-Co bonding, which facilitates electron transfer, leading to an abundant presence of Co³⁺ ions and active oxygen species in the CoNi/NF composite; consequently, the catalyst exhibited improved redox capabilities. In this study, significant enhancements in the surface physicochemical properties of the Co-based catalyst were achieved through optimization of its chemical composition and micromorphology, offering a feasible solution for the effective removal of VOCs.