Plasma‐Catalytic CO ₂ Methanation Over a Ni Particle Size Tunable NiAl Catalyst

The reaction mechanism of plasma‐catalytic CO 2 methanation remains unclear, especially regarding the Ni size effect. To address this, a tunable NiAl catalyst was explored. A linear correlation exists between methanation activity and Ni particle size: CO 2 conversion increases with larger Ni particles. The NiAl‐300 catalyst (5.8 nm) achieved 86% CO 2 conversion and 100% CH 4 selectivity, while NiAl‐500 (2.6 nm) reached only 63% and 98%, respectively. In situ DRIFTS revealed that larger Ni particles promote hydrogenation of formate and HCO species due to their efficient utilization of plasma‐induced H radicals. This work provides theoretical support for rationally designing efficient catalysts in plasma‐catalytic CO 2 methanation systems.