MOF-derived hierarchical hollow spheres composed of carbon-confined Ni nanoparticles for efficient CO2 methanation

Abstract

The hydrogenation of CO₂ to CH₄ is attracting growing attention due to the universal energy and climate challenges. In this work, we present the facile synthesis of hierarchical Ni@C spheres composed of dispersed Ni nanoparticles confined in carbon shells as an efficient catalyst for low-temperature CO₂ methanation at ambient pressure. With Ni-based metal–organic frameworks (MOFs) as a precursor, the Ni@C composite was produced by thermal annealing in a N₂ atmosphere. The MOF-derived Ni@C hybrid with unique hollow and porous structures could afford high surface area and rich isolated active sites for CO₂ adsorption/activation and redox processes. Therefore, the Ni@C catalyst exhibited high activity, excellent selectivity and superior stability for CO₂ methanation reaction. The possible intermediates and reaction pathway of the CO₂ conversion catalysis were carefully investigated by CO₂-TPD measurements and in situ FTIR characterization. Furthermore, a possible CO₂ methanation mechanism over the Ni@C catalyst was proposed.