Decoupling Activity‐Selectivity Trade‐off in Photothermal Catalytic CO 2 Hydrogenation: A Hydrogen Spillover‐Assisted Dual‐Site Synergy Mechanism

Abstract The persistent trade‐off between catalytic activity and selectivity remains a critical barrier to efficient CO 2 valorization. Herein, we propose a concept of decoupling the activity‐selectivity trade‐off in the photothermal catalytic reverse water‐gas shift (RWGS) reaction by hydrogen spillover‐assisted dual‐site synergy. This concept is demonstrated through a hybrid catalyst constructed by immobilizing abundant Ru single sites and trace Ru clusters onto high‐efficiency photothermal support of N‐doped hierarchical carbon nanocages (hNCNC). Theoretical calculations reveal that the Ru─N 4 sites are highly active and selective for the RWGS reaction, contingent on the efficient migration of dissociated *H species to adjacent C atoms of Ru. Importantly, we experimentally confirm that Ru single sites dominate CO 2 hydrogenation to CO, whereas Ru clusters facilitate H₂ activation and supply hydrogen species to adjacent single sites via spillover over hNCNC. Leveraging this synergistic interaction, the hybrid catalyst achieves an exceptional CO production rate of 3.1 mol·g Ru −1 ·h −1 and selectivity over 98%. This mechanism shows universal applicability as demonstrated by the effective promotion of CO 2 hydrogenation of Ru single sites by other typical hydrogen‐spillover‐active metal clusters, e.g., Pt and Pd clusters. This design concept liberates the potential to overcome the longstanding activity‐selectivity trade‐off in hydrogenation reactions.