Enhanced CO^* Adsorption via In Situ Phase Transition of Ni/NiAlO_x Catalyst for Photothermal CO₂ Methanation

The catalytic hydrogenation of carbon dioxide (CO₂) into high-value methane (CH₄) via photothermal catalysis is a promising strategy for mitigating carbon emissions and addressing the energy crisis. This study details the synthesis of Ni/NiAlO_x nanocatalysts via the in situ topological reduction of a layered double hydroxide (NiAl-LDH) precursor, and further examines the influence of the interface structure on the reaction pathway and overall catalytic performance. The Ni/NiAlO_x-500 catalyst demonstrated a CO₂ conversion rate of 84.5%, CH₄ selectivity of 99.5%, and CH₄ production rate of 654 mmol·h^-1·g_cat^-1 under photothermal conditions at 330 °C. Notably, it remains highly effective, with a CH₄ production rate of 68.8 mmol·h^-1·g_cat^-1 even at a reduced temperature of 210 °C. In situ DRIFT spectroscopy revealed the mechanism by which interface engineering modulates reaction intermediates. The Ni(Al)O_x-500 catalyst achieves efficient H₂ dissociation through abundant Ni cluster sites, while the oxide-interfacial-structure-promoted strong metal-support interactions (SMSI) enable robust CO* adsorption. This synergy facilitates CO₂ hydrogenation via HCOO* and CO* as key intermediates. This study elucidates the structure-activity relationship with respect to induction temperature, interface structure, and reaction pathway, offering a strategy for the design of low-temperature, high-efficiency CO₂ conversion catalysts.