Photochemical route for synthesizing atomically dispersed palladium catalysts
Lightly dispersed palladium Catalysts made from atomically dispersed metal atoms on oxide supports can exhibit very high per atom activity. However, the low loadings needed to prevent metal particle formation can limit overall performance. Liu et al. stably decorated titanium oxide nanosheets with relatively high loadings of single palladium atoms by reducing the ions with ultraviolet light and ethylene glycol. These catalysts cleaved H2 into atoms and were highly effective for hydrogenating alkenes and aldehydes. Science, this issue p. 797 Ultraviolet light and ethylene glycol enable decoration of titanium oxide nanosheets with high loading of palladium atoms. Atomically dispersed noble metal catalysts often exhibit high catalytic performances, but the metal loading density must be kept low (usually below 0.5% to avoid the formation of metal nanoparticles through sintering. We report a photochemical strategy to fabricate a stable atomically dispersed palladium titanium oxide catalyst (Pd1/TiO2) on ethylene glycolate (EG) stabilized ultrathin TiO2 nanosheets containing Pd up to 1.5% The Pd1/TiO2 catalyst exhibited high catalytic activity in hydrogenation of C=C bonds, exceeding that of surface Pd atoms on commercial Pd catalysts by a factor of 9. No decay in the activity was observed for 20 cycles. More important, the Pd1/TiO2 EG system could activate H2 in a heterolytic pathway, leading to a catalytic enhancement in hydrogenation of aldehydes by a factor of more than 55.
Science