Volcanic relationship between Co-carbon layer interaction strength and catalytic activity for olefin hydroformylation

Metal-support interaction (MSI) is of great significance for designing the supported metal catalysts with high catalytic activity and selectivity. In this work, the MSI between Co and the carbon layer in armored cobalt nanoparticle catalysts (Co@xC) is effectively regulated based on the channel confinement strategy. Notably, a direct volcanic relationship could be obtained between the MSI strength of catalysts and the reaction rate constant. The Co@2.5C catalyst with suitable MSI strength achieves complete 1-hexene conversion (100%) and the yield of heptanal is 17,161 mol kg_Co⁻¹ h⁻¹ during the 1-hexene hydroformylation reaction. Further in situ/ex situ characterizations combined with theoretical calculations confirm the appropriate MSI accelerates the electron transfer from the carbon atom to the Co site, thereby enhancing the adsorption of 1-hexene species and boosting the reaction kinetics (the first-order reaction rate constant is 0.017 min⁻¹). The volcanic structure-activity relationship in this work exhibits guiding significance for the development of industrial catalysts.