Deciphering the Dual CO ₂ Methanation Mechanism Over Cobalt Decorated Ni Spinel

ABSTRACT

The methanation of CO ₂ represents a promising strategy for carbon capture utilization and renewable energy storage, yet developing catalysts that combine high low‐temperature activity, selectivity, and stability remains a significant challenge. Here, we report a cobalt‐promoted thermally stable NiAl ₂ O ₄ (NAO) catalyst (5%Co/NAO) that addresses these limitations. The incorporation of Co induces profound changes in both the electronic structure and the reaction mechanism. The electronic modulation enhances metal‐support and metal‐metal interactions, promoting the formation of small Ni nanoparticles and oxygen vacancies. Critically, in situ DRIFTS demonstrates that the addition of Co switches the reaction pathway from a single associative (formate) route on pristine NAO to a dual associative‐dissociative pathway on 5%Co/NAO, involving both formate (HCOO*) and CO* intermediates. The presence of the CO* pathway accelerates low‐temperature CO ₂ activation and the rate‐limiting hydrogenation of HCOO* to CHO*. Consequently, 5%Co/NAO achieves 18% CO ₂ conversion at 220°C and 89% at 300°C, with a lower apparent activation energy (81.20 kJ mol ⁻¹ ) and a CH ₄ selectivity of ∼93%. The catalyst also exhibits outstanding stability without sintering or coking during 100 h tests. This work establishes that Co‐Ni synergy and enabling a dual reaction pathway, offers a powerful design strategy for efficient low‐temperature CO ₂ methanation catalysts.