Microwave synthesis of a bimodal mixture of triangular plate and spheroidal silver nanoparticles

A bimodal mixture of silver nanoparticles consisting of spheres and triangular nanoplates was synthesized from silver nitrate (AgNO₃) and polyvinylpyrrolidone with the aid of a microwave reactor system, reducing total reaction time from days to minutes; a specific shape-directing reagent was not used. It is known that freshly prepared solutions of AgNO₃ contain a high population of Ag₃⁺, while aged solutions contain fewer trimers. We propose that the product ratios of spheroidal to triangular particles are proportional to the relative population of trimers in solution prior to initiation of the microwave reaction.