Enhanced CO* Adsorption via In Situ Phase Transition of Ni/NiAlOx 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/NiAlOx 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/NiAlOx-500 catalyst demonstrated a CO2 conversion rate of 84.5%, CH4 selectivity of 99.5%, and CH4 production rate of 654 mmol·h-1·gcat-1 under photothermal conditions at 330 °C. Notably, it remains highly effective, with a CH4 production rate of 68.8 mmol·h-1·gcat-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)Ox-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.