Niobium Modification of CeO2Tuning Electron Density of Nickel–Ceria Interfacial Sites for Enhanced CO2Methanation

CO2methanation has attracted considerable attention as a promising strategy for recycling CO2and generating valuable methane. This study presents a niobium-doped CeO2-supported Ni catalyst (Ni/NbCe), which demonstrates remarkable performance in terms of CO2conversion and CH4selectivity, even when operating at a low temperature of 250 °C. Structural analysis reveals the incorporation of Nb species into the CeO2lattice, resulting in the formation of a Nb–Ce–O solid solution. Compared with the Ni/CeO2catalyst, this solid solution demonstrates an improved spatial distribution. To comprehend the impact of the Nb–Ce–O solid solution on refining the electronic properties of the Ni–Ce interfacial sites, facilitating H2activation, and accelerating the hydrogenation of CO2* into HCOO*, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis and density functional theory (DFT) calculations were conducted. These investigations shed light on the mechanism through which the activity of CO2methanation is enhanced, which differs from the commonly observed CO* pathway triggered by oxygen vacancies (OV). Consequently, this study provides a comprehensive understanding of the intricate interplay between the electronic properties of the catalyst’s active sites and the reaction pathway in CO2methanation over Ni-based catalysts.