Abstract
<jats:p>CO2 methanation is a promising strategy for CO2 utilization and renewable energy storage. Although CeO2-supported Ni catalysts are widely regarded as the benchmark systems for this reaction, the origin of the promotional effect of ceria remains elusive because conventional Ni/CeO2 catalysts contain structurally heterogeneous CeO2 domains that obscure the nature of the active sites. Here, we employ a surface organometallic chemistry/thermolytic molecular precursor (SOMC/TMP) strategy to construct a model NiCe@SiO2 catalyst featuring well-defined interfacial sites between Ni nanoparticles and Ce(III) species, thereby enabling direct evaluation of their role in CO2 methanation. The incorporation of Ce(III) sites significantly enhances the methanation activity of Ni catalysts. In situ X-ray absorption spectroscopy confirms the absence of NiCe alloy formation under either reduction or reaction conditions, while in situ diffuse reflectance infrared Fourier transform spectroscopy and steady-state isotopic transient kinetic analysis reveal that Ni–Ce(III) interfacial sites promote a formate-mediated pathway that is substantially more active than the CO-mediated pathway on Ni nanoparticles. These findings identify interfacial Ce(III) species as key promoters for CO2 methanation and provide molecular-level insights into the rational design of efficient metal-oxide catalysts.</jats:p>