A self-seeding synthesis of Ag microrods of tuned aspect ratio: ascorbic acid plays a key role

Control of the shape and size of nanoparticles is crucial for using them as labels or as building blocks in nanotechnology. In fact, silver has so far been considered as having the widest variety of different morphologies at the nano-scale and micro-scale levels. To make progress in these criteria, in our paper we have synthesized highly reproducible silver (Ag) microrods of controlled aspect ratios through a rapid self-seeding method. The Ag nano seeds are formed via the reduction of Ag ions in hot ethylene glycol by ascorbic acid, and the subsequent growth of microrods is controlled by further deposition of Ag atoms in the presence of poly(vinylpyrrolidone). Moreover, ascorbic acid is exclusively responsible for the rod morphology, as we describe here in detail. A very low concentration of ascorbic acid forms very few Ag microrods along with a majority of Ag colloidal particles, while random overgrowth on the surfaces is observed for higher concentrations. The critical reaction...

Nikunjkumar Visaveliya and J Michael Köhler

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