Halide Ion Effect in Shape Transformation from Silver Triangular Nanoprisms to Silver Nanodisks

摘要

Silver triangular nanoprisms (TNP's) were transformed into silver nanodisks (NDK's) by addition of halide ion solution (chloride, bromide and iodide). The shape transformation of the TNP's is due to the selective etching effect of halide ions at their vertices. TNP's were synthesized via a photoinduced growth process, and then different concentrations of potassium halide solutions were added into the TNP's colloids under vigorous stirring. Images of the obtained nanoparticles were recorded by scanning electron microscopy (SEM). The shifts of the in-plane dipole plasmon resonance band allow us to identify the differences among the three halides. These differences might be due to the distinct sizes of halides, and the solubility product constant values of each silver halide. We found that the etching ability of the halides, at a concentration of 1.0 mM, to truncate the vertices of TNP's is in the order of Br~- > Cl~- > I~-. In contrast, at a concentration of 0.01 mM, the order of the etching ability is Br~- > I~- > Cl~-.