Accelerating Hydrogen Spillover on Cu^δ+/Ru^δ+-O_v-Ce³⁺ Tandem Sites for Enhanced Photothermal CO₂ Methanation

Photothermal CO₂ methanation represents a promising strategy for sustainable fuel synthesis under mild conditions, yet its efficiency remains constrained by the kinetic mismatch between CO₂ activation and active H delivery. Herein, we constructed atomically dispersed Cu^δ+/Ru^δ+ tandem sites anchored on the oxygen-vacancy-rich CeO₂(111) surface. Advanced characterizations verify the coordination of both metals within the CeO₂ lattice, forming a well-defined dual-site configuration. Under simulated solar irradiation, the optimized catalyst achieves a remarkable CH₄ production rate of 4.92 mmol·g_cat ^-1·h^-1 at a moderate surface temperature of 349.6°C while maintaining excellent long-term stability. Through a combination of in situ spectroscopic studies, catalytic evaluations, and density functional theory calculations, we elucidate a synergistic tandem mechanism, in which Cu^δ+ sites facilitate CO₂ adsorption and primary activation, while adjacent Ru^δ+ sites promote H₂ dissociation and subsequent hydrogen spillover. This spatially coupled process ensures efficient transfer of active hydrogen species to the reaction intermediates, dramatically accelerating the cleavage of the C─O bond and the intermediates hydrogenation. This work offers atomistic insights into bifunctional synergy, establishing a design paradigm for efficient CO₂ conversion photothermal catalysts.