Monodisperse Ag/Pd core/shell nanoparticles assembled on reduced graphene oxide as highly efficient catalysts for the transfer hydrogenation of nitroarenes.

Addressed herein is a facile seed-mediated synthesis of Ag/Pd core/shell nanoparticles (NPs) and their assembly on reduced graphene oxide (rGO) to catalyze the transfer hydrogenation of nitroarenes to anilines using ammonia borane (AB) as a hydrogen donor under ambient conditions. Monodisperse Ag/Pd core/shell NPs with controllable Pd shell-thickness were synthesized by the means of thermal decomposition of palladium(II) bromide over as-prepared Ag NPs in the mixture of oleylamine and oleic acid at 220°C. As-synthesized Ag/Pd core/shell NPs were characterized by TEM, HR-TEM, XRD, XPS, UV-Vis spectroscopy and ICP-MS and then they were assembled on reduced graphene oxide (rGO). Next, rGO@Ag/Pd catalysts were tested in the transfer hydrogenation of nitroarenes in which ammonia borane (AB) was used as a hydrogen donor at room temperature. It was demonstrated that the thickness of the Pd shell has a significant effect on the catalytic activity of rGO@Ag/Pd catalysts and the 1.75nm Pd shell provided the highest performance in the transfer hydrogenation reactions. The rGO@Ag/Pd catalyzed transfer hydrogenation reactions were tested over a variety of nitroarenes (total 16 examples) and they were all converted to the corresponding aniline derivatives with high yields in 5-15min under ambient conditions.