Small-sized Ag nanocrystals: high yield synthesis in a solid–liquid phase system, growth mechanism and their successful application in the Sonogashira reaction

Abstract

In this paper, small-sized monodisperse Ag nanocrystals (NCs) have been successfully synthesized at gram-scale by thermal reduction of a large amount of solid AgNO₃ (more than 10 mmol) with dodecylamine in 1-octadecene solvent. The formation process of the Ag NCs is different from that of a conventional homogeneous phase synthetic system. According to the temperature- and time-dependent experiments, a high temperature “digestive ripening” mechanism is suggested to elucidate their formation process. The size of Ag NCs can be easily controlled by the amount of solid AgNO₃ added and the reaction temperature. Furthermore, the obtained Ag NCs are found to possess extraordinary catalytic activity, which can catalyze a series of Sonogashira reactions with high yield. Interestingly, under identical conditions, their catalytic activities are higher than that of similar sized Pd NCs, showing great promise for the substitution of conventional Pd-based catalysts to apply in the Sonogashira reaction. This developed synthetic strategy together with the fundamental understanding of heterogeneous nucleation and growth has great potential towards the contriving rational route for mass production of nanomaterials for advanced catalytic and other functional applications.