Influence of Anions of the Hofmeister Series on the Size of ZnS Nanoparticles Synthesised via Reverse Microemulsion Systems

摘要

Zinc sulfide nanocrystals with sizes of 4-7 nm were obtained by insufflation of hydrogen sulfide through reverse microemulsions, based on aqueous solutions of different zinc salts, nonionic surfactants and cyclohexane. The influence of the Hofmeister anions acetate, chloride, bromide, nitrate, iodide, and perchlorate on the micelles and thereof formed nanoparticles was studied by means of dynamic light scattering (DLS), X-ray diffractometry (XRD), UV-Vis spectroscopy and transmission electron microscopy (TEM). The sizes of micelles are significantly influenced by the kosmotropic or chaotropic nature of the actual anion, present in the water pools of reverse micelles: the diameter of the spherical ZnS nanoparticles, synthezised in these micelles, correlates with their size and thus follows the direction of the Hofmeister series. Several possible mechanisms are proposed to explain the influence of the anions.