Strong interface interaction enriched surface Co³⁺ cations on Co₃O₄-LaCoO₃ composite catalyst for highly efficient toluene oxidation

Interface interaction existed in the multicomponent determines the catalytic performance of composite catalysts. Herein, a Co₃O₄-LaCoO₃ (Co-La) composite catalyst with strong spinel-perovskite interface interaction was successfully synthesized via a one-pot sol-gel method for the catalytic oxidation of toluene. The activity test results showed that the optimal 1Co₃O₄–4LaCoO₃ (1Co-4La) catalyst exhibits much higher catalytic activity (T₉₀ = 215 °C, GHSV = 50,000 h⁻¹) than Co₃O₄ (T₉₀ = 295 °C), LaCoO₃ (T₉₀ = 256 °C) and 1Co₃O₄/4LaCoO₃ (1Co/4La) (prepared by mechanical ball-milling, T₉₀ = 285 °C). Characterizations revealed that the strong spinel-perovskite interface interaction generated between the Co₃O₄ spinel and LaCoO₃ perovskite in 1Co-4La facilitates the transfer of interfacial electrons, contributing to the exposure of surface active Co³⁺ and the enhanced oxidation ability of surface active Co³⁺ on 1Co-4La. In addition, the reactive lattice oxygen of surface Co³⁺–O on 1Co-4La effectively promotes the decomposition of toluene into CO₂, enabling the low-temperature oxidation of toluene through the Mars-van Krevelen (MvK) mechanism. This work provides insight into the promotional effect of multicomponent interface interaction on enhancing catalytic performance of spinel-perovskite composite catalysts.