Substituted LaNiO₃ Perovskites for Efficient CO₂ Methanation: Unveiling the Synergy of Basicity and Oxygen Storage

Carbon dioxide mitigation has become a challenging concern as the world increasingly focuses on carbon neutrality. Producing high hydrogen storage density materials (such as CH4) from CO2 using catalytic hydrogenation is widely considered an efficient and promising route to tackle the gas in substantial amounts and carbon recycling. Ni-based materials have been the focus of several implementation strategies due to their low cost, high compatibility, and high activity. Small and highly dispersed active species are coke-resistant and resistive to thermal sintering; such compositions can be easily derived from perovskite-type materials. A hydrothermal approach has been implemented to synthesize LaNiO3 and its derivatives via A/B-site partial substitution. Glycine is used as a structure-directing agent to achieve a nanocube-type shape, and a purely polycrystalline perovskite structure is obtained in an oxygen atmosphere during calcination. The structure–activity relationship is established through various catalyst characterization techniques (XRD, TPR, CO2-TPD, OSC, TGA, SEM, and TEM analysis). The combined effect of moderate basicity and high oxygen storage capacity helps achieve higher catalytic activity of La0.9Sm0.1NiO3 for CO2 methanation. Partial replacement of Sm in the base catalyst leads to 89% CO2 conversion with 100% CH4 selectivity for a long span tested up to 200 h without deactivation. The TPSR study provides evidence that the carbon dioxide activation proceeds through a dissociative mechanism as CO and O* intermediates, which is further assisted by insitu DRIFT studies.