Unveiling the Metal-Oxide Interface as a Prerequisite for Structural Sensitivity in CO₂ Hydrogenation on Ni Catalysts

Supported nickel (Ni) catalysts are widely utilized in industrial CO/CO₂ hydrogenation for methane production. However, their structural sensitivity presents a significant challenge to productivity. While larger Ni particles generally favour methane formation, unsupported Ni nanoparticles (even at the micrometre scale) fail to efficient CO₂ methanation. In this study, we engineered TiO₂@Ni-x catalysts by depositing TiO₂ onto Ni surface, along with conventional Ni/TiO₂ and unsupported Ni nanoparticles (Ni-p), to explore the synergy of multi-sites in CO₂ hydrogenation. The TiO₂@Ni-x achieved 90.1% methane selectivity at 400 °C, while CO dominated on both Ni-p and Ni/TiO₂. Temperature programmed experiments, in-situ infrared spectroscopy and theoretical modelling results revealed that TiO₂@Ni-x with metal-oxide interfaces integrate excellent capabilities for H₂, CO₂, and CO adsorption and dissociation, enabling a complete hydrogenation pathway and high CH₄ selectivity. The reactivity of CO intermediates is predominantly governed by the abundance of Ni-TiO₂ interfaces and the formation of Ni-C-O-Ti bridge configurations, rather than isolated Ni surfaces. In contrast, despite having interfaces, conventional Ni/TiO₂ suffered from strong metal- support interactions (SMSI) with limited H₂