A comparative study of the effect of metal-support interaction on catalytic CO₂ methanation over Ni/Ce_xZr1_-xO₂ catalysts under thermal and plasma conditions

Metal-support interaction (MSI) is a well-established strategy for tuning catalytic activity in thermal catalysis, yet its role in nonthermal plasma catalytic CO₂ methanation remains insufficiently explored. In this study, the Ni/CeₓZr₁₋ₓO₂ catalysts were synthesized using CeₓZr₁₋ₓO₂ supports calcined at different temperatures to systematically modulate MSI. A volcano-shaped correlation was observed between catalytic activity and support calcination temperature in both thermal and plasma systems. The CeₓZr₁₋ₓO₂ support calcined at 600 °C, having a moderate particle size, demonstrated optimum MSI (i.e., promoting the facile formation of oxygen vacancies and stable interfacial anchoring of Ni particles) and thus the comparatively best catalytic performance under both conditions. Under the tested conditions, thermal CO₂ methanation exhibited superior activity compared to plasma-assisted reactions; e.g., over the NCZ-600 catalyst it achieved an 83% CH₄ yield at 350 °C versus 11.3% at 7.0 kV. These results underscore the critical role of MSI in governing CO₂ methanation across distinct catalytic environments and highlight its potential as a unifying design principle.