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

The persistent trade-off between catalytic activity and selectivity remains a critical barrier to efficient CO₂ 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─N₄ 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 CO₂ 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 CO₂ 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.