Isolated Ni Atoms Enable Near-Unity CH 4 Selectivity for Photothermal CO 2 Hydrogenation.

Photothermal hydrogenation of carbon dioxide (CO 2 ) into value-added products is an ideal solution for addressing the energy crisis and mitigating CO 2 emissions. However, achieving high product selectivity remains challenging due to the simultaneous occurrence of numerous competing intermediate reactions during CO 2 hydrogenation. We present a novel approach featuring isolated single-atom nickel (Ni) anchored onto indium oxide (In 2 O 3 ) nanocrystals, serving as an effective photothermal catalyst for CO 2 hydrogenation into methane (CH 4 ) with a remarkable near-unity (∼99%) selectivity. Experiments and theoretical simulations have confirmed that isolated Ni sites on the In 2 O 3 surface can effectively stabilize the intermediate products of the CO 2 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 CO 2 to methane.