Photo-induced morphological conversions of silver nanoparticles prepared using laser ablation in water—Enhanced morphological conversions using halogen etching

Our previous report showed that chloride ions enhanced photo(laser and fluorescent-light)-induced morphological conversions of silver nanoparticles prepared using laser ablation in pure water, in which spherical particles were converted to crystal-shaped nanoparticles such as nanoprisms or nanorods. In the present study, we investigated the morphological conversion of nanoparticles in iodide solutions and that of smaller nanoparticles in chloride solutions. In addition to the formation of crystal-shaped particles in photo-irradiated conditions, marked morphological changes in the dark conditions were observed in these solutions, which was different from the results of the previous study. Besides, the formation of AgI and AgCl2− was also detected. These findings confirm that halogen etching of silver plays a critical role in the morphological conversions. Photoirradiation at various wavelengths was also carried out to investigate the role of the photoirradiation. The formation of the crystal-shaped particles that occurred even by long wavelength (700 nm) irradiation indicates that the photoirradiation might control the interaction between silver atoms and the nanoparticle surface via electronic field excitation rather than the reduction rate of silver ions.