Inverse Ni/CeCrOx Catalysts for Enhanced Low-Temperature CO2 Methanation.

Low-temperature methanation technology offers a promising pathway for carbon recycling and sustainable energy storage by enabling near-equilibrium CO2 conversion under atmospheric pressure. However, efficiently activating CO2 at low temperatures remains a significant challenge due to the kinetic limitations of hydrogenation intermediates. We construct a composite oxide-metal interface structure by anchoring highly dispersed CeCrOx nanoclusters onto metallic nickel via an ion-exchange method. This catalyst exhibits superior activity compared to conventional Ni/oxide catalysts with identical composition. Under atmospheric pressure at 220 °C, it achieves nearly 80% CO2 conversion with over 99% methane selectivity and maintains excellent catalytic performance and structural stability during a 240-h continuous test. Systematic characterizations, including high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, CO2 temperature-programmed desorption, and in situ DRIFTS reflectance infrared Fourier-transform spectroscopy, reveal that the synergistic modification by CeO2 and Cr2O3 not only optimizes the electronic structure of Ni to promote CO2 adsorption and activation, but also enhances H2 dissociation and intermediate conversion by regulating oxygen vacancy concentration and alkaline site distribution. Mechanistic studies indicate that the reaction follows a synergistic mechanism dominated by the formate pathway and assisted by the CO pathway. Moreover, the interfacial structure effectively stabilizes active sites and inhibits carbon deposition from CH4 decomposition. This study provides a universal and effective strategy for designing Ni-based CO2 conversion catalysts suited for mild reaction conditions and characterized by high energy efficiency.