Titania supported synergistic palladium single atoms and nanoparticles for room temperature ketone and aldehydes hydrogenation

Selective reduction of ketone/aldehydes to alcohols is of great importance in green chemistry and chemical engineering. Highly efficient catalysts are still demanded to work under mild conditions, especially at room temperature. Here we present a synergistic function of single-atom palladium (Pd-1) and nanoparticles (Pd-NPs) on TiO2 for highly efficient ketone/aldehydes hydrogenation to alcohols at room temperature. Compared to simple but inferior Pd-1/TiO2 and Pd-NPs/TiO2 catalysts, more than twice activity enhancement is achieved with the Pd1+NPs/TiO2 catalyst that integrates both Pd-1 and Pd NPs on mesoporous TiO2 supports, obtained by a simple but large-scaled spray pyrolysis route. The synergistic function of Pd-1 and Pd-NPs is assigned so that the partial Pd-1 dispersion contributes enough sites for the activation of C=O group while Pd-NPs site boosts the dissociation of H-2 molecules to H atoms. This work not only contributes a superior catalyst for ketone/aldehydes hydrogenation, but also deepens the knowledge on their hydrogenation mechanism and guides people to engineer the catalytic behaviors as needed.