Isolated Ni Atoms Enable Near-Unity CH4 Selectivity for Photothermal CO2 Hydrogenation.

Photothermal hydrogenation of carbon dioxide (CO₂) into value-added products is an ideal solution for addressing the energy crisis and mitigating CO₂ emissions. However, achieving high product selectivity remains challenging due to the simultaneous occurrence of numerous competing intermediate reactions during CO₂ hydrogenation. We present a novel approach featuring isolated single-atom nickel (Ni) anchored onto indium oxide (In₂O₃) nanocrystals, serving as an effective photothermal catalyst for CO₂ hydrogenation into methane (CH₄) with a remarkable near-unity (∼99%) selectivity. Experiments and theoretical simulations have confirmed that isolated Ni sites on the In₂O₃ surface can effectively stabilize the intermediate products of the CO₂ hydrogenation reaction and reduce the transition state energy barrier, thereby changing the reaction path to achieve ultrahigh selective methanation. This study provides comprehensive insights into the design of single-atom catalysts for the highly selective photothermal catalytic hydrogenation of CO₂ to methane.