Evidence of an aggregative mechanism during the formation of silver nanowires in N,N-dimethylformamide

A detailed high-resolution electron microscopy study of the formation of Ag nanowires by solvent reduction in N,N-dimethylformamide (DMF), in the presence of poly(vinylpyrrolidone) (PVP) at high temperature provided clear evidence that the nanowires grow through the oriented aggregation of precursor nanoparticles. The HRTEM images demonstrate that initially, icosahedral and cuboctahedral Ag nanoparticles are formed, which then self-assemble to form aligned stripes, and eventually fuse with each other to yield single crystalline nanowires. The nanoparticle aggregation only takes place through preferred facets of the original nanocrystals, and therefore intermediate twisted wires are observed.