Synergies Between Atomically Dispersed Ru Single Atoms and Nanoparticles on CeAlOx for Enhanced Photo-Thermal Catalytic CO₂ Hydrogenation.

Abstract

Heterogeneous catalysts integrating single-atom species and nanoparticles maximize atom utilization and hydrogen dissociation for hydrogenation reactions. However, challenges in maintaining consistent metal loadings during synthesis complicate direct performance comparisons with the single-atom and nanoparticle-based systems, which obscures rational assessment of their catalytic potential. Herein, Ru_1+NPs/CeAlO_x photothermal catalysts are reported which leverage the synergy between Ru single atoms and Ru nanoparticles to enhance CO₂ hydrogenation to CH₄. Under light irradiation (3.1 W cm^-2, 200-1100 nm) at 200 °C, the Ru_1+NPs/CeAlO_x catalyst achieves a CH₄ production rate of 197.2 mmol g_cat ^-1 h^-1 with near-100% selectivity, surpassing single-atom Ru₁/CeAlO_x catalysts and nanoparticle-based Ru_NPs/CeAlO_x catalysts, with equivalent metal contents. Mechanistic studies revealed that in Ru_1+NPs/CeAlO_x catalysts, Ru single atoms facilitate CO₂ adsorption/activation and subsequent conversion, while Ru nanoparticles promote H₂ dissociation, with their synergistic interplay driving superior performance. Moreover, the CeAlO_x support effectively stabilizes the dual-site structure and facilitates the formation of reaction intermediates through its abundant oxygen vacancies and surface Lewis acid-base pairs, thereby further enhancing the catalytic reaction. This work highlights the critical role of synergistic effects between single atoms and nanoparticles, offering new approaches for designing high-efficiency hydrogenation catalysts.