MOF encapsulated sub-nm Pd skin/Au nanoparticles as antenna-reactor plasmonic catalyst for light driven CO2 hydrogenation

Highlights: • UiO-66-NH₂ encapsulated Au@Pd NPs was used for light driven CO₂ hydrogenation. • The sub-nm Pd skin delays the dissipation of energy gained from photon absorption. • The Pd skin reduces the reaction energy barrier from CO₂* to COOH*. Activation of CO₂ with plasmon induced hot electrons has attracted great attention due to its moderate reaction conditions, but high-efficiency plasmonic catalysts still remains challenging. Herein, we designedly prepared an antenna-reactor plasmonic catalyst with core-shell structure, i.e. sub-nm Pd skin/Au NPs encapsulated within UiO-66-NH₂ (Au@Pd@UiO-66-NH₂-0.5) for CO₂ hydrogenation under light-heat dual activation. Under the photo-thermal synergism, CO₂ can be efficiently converted into CO and the optimal production rate reaches 3737 µmol/g_metal/h at 150 °C. Thereinto, ultrafast transient absorption spectroscopy reveals that the sub-nm Pd skin provides a longer time window for hot electron transfer and efficient retardation of energy dissipation. Theoretical calculations further confirm the significant reductions in HOMO-LUMO gap of CO₂ and reaction energy barrier from CO₂* to COOH* through adsorption of CO₂ on sub-nm Pd skin, promoting its efficiency and selectivity. Our findings provide new insights into design of bimetallic plasmonic catalysts for low-temperature catalysis.