Metal-support interface configuration dictates the CO₂ hydrogenation pathway on nickel-based catalysts

Metal-support interface configuration is prevalent in metal/support catalytic systems, significantly influencing the adsorption-activation-reaction process of reactant species. The controllable modulation of interaction strength is advantageous for a deeper understanding of the catalytic behaviors over active sites. In this study, nickel species (Ni) were doped into the bulk phase of MnO₂ via one-step solid-phase method, allowing for the modulated Ni-MnO interface and interaction strength after reduction. The NiMn-S1 catalyst, exhibiting weaker interactions, showed an average Ni particle size of 20.4 nm and CO selectivity of 93.7% at 400 °C. In contrast, the NiMn-S3 catalyst with stronger interactions by forming a NiMnO_x composite oxide at the Ni-MnO interface, leading to a lower average Ni particle size of 12.5 nm with decreased CO selectivity of 42.3%. Systematic studies revealed that the weaker interaction NiMn-S1 catalyst underwent the carboxylate pathway during the CO₂ hydrogenation reaction and its following decomposition into CO product, while the more strongly interacted NiMn-S3 catalyst exhibited significantly enhanced CO₂, intermediate CO adsorption and dissociation, facilitating more efficient hydrogenation to CH₄ product. It is suggested that the gradually altered NiMn interface interactions were significantly responsible for the tuned selectivity instead of conventionally considered structural sensitivity during CO₂ hydrogenation reaction. This study suggested a new insight of the importance of modulated Ni-support interaction by interface engineering to achieve a boosted intermediate adsorption, activation in CO₂ hydrogenation.