Sculpturing effect of sodium thiosulfate in shape transformation of silver nanoparticles from triangular nanoprisms to hexagonal nanoplates.

Sodium thiosulphate (Na2S2O3) solution was used to etch silver nanoparticles (NPs) and transform them from triangular nanoprisms to hexagonal nanoplates. UV-Vis spectroscopy and transmission electron microscopy were used to monitor the evolution of the hexagonal Ag nanoplates. S2O3(2-) etched the corners of the triangular Ag nanoprisms, and the Ag atoms that were removed aggregated into small clusters. The facet-selective etching effect of S2O3(2-) can be mainly attributed to the surface energy difference of each face of the nanoplate. The mechanism of S2O3(2-) etching also involves formation of Ag2S2O3 on the nanoprisms vertices, which is followed by its hydrolysis and subsequent dissociation of Ag atoms to form stable Ag2S. The hexagonal Ag nanoplates showed higher surface-enhanced Raman scattering activity than the original nanoprisms.