Electron transfer-induced hydrogenation of anthracene catalyzed by gold and silver nanoparticles

Anthracene hydrogenation in aqueous micellar solutions is catalyzed at room temperature by ionic-surfactant-protected gold and silver nanoparticles (NPs) with well-controlled particle sizes. When sodium borohydride was used as the hydrogen source in the presence of these NPs, the only product obtained in the reaction is 9,10-dihydroanthracene. During the course of the reaction, a blue shift in the surface plasmon resonance band of silver NPs was more prominent and lasted longer than that of gold NPs. The difference in the optical property of metal NPs was related to the charging of their surfaces, indicating that the metal NPs play a role as the nanoelectrode storing electrons from hydrides. At the same time, a remarkable size-dependence of catalytic activity was found for both gold and silver NPs. Mechanism about the electron transfer-relaying effects of metal NPs is proposed for the hydrogenation reaction.