Effects of Anionic Surfactants on Crystal Growth of ZnO

Abstract

The synthesis of one dimensional (1D) ZnO nanostructures with various shapes such as nanorods, nanowires, nanobelts, nanotubes and nanoribbons have been received significant attention because of their considerable chemical and physical properties, and possibility of wide applications in nanoscale devices. Then, many other groups investigated additives including surfactants and polymers to control various size and shapes of ZnO nanocrystals. In this study, we used anion surfactants which have the same length of carbon chain with different counter-ions (head groups), such as sodium dodecyl sulfate (SDS), ammonium dodecyl sulfate (ADS) and lithium dodecyl sulfate (LDS), and investigated the effects of anionic surfactants on crystal growth of ZnO. The crystal growth mechanism of ZnO with nanowires and nanobelts can be clearly understood on the basis of the interactions between negatively charged zinc hydrate precursors and counter-ions of anionic surfactants. It is observed that the use of anionic surfactants as additives can reduce surface energy of specfic crystal faces by adsorption of their counter-ion on the surface of negatively charged zinc hydrate precursor and it can assist to control the crystal growth. The crystal structure and morphologies of ZnO were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), High-Resolution Transmission Electron Microscopy (HRTEM) and X-Ray Diffraction (XRD). The Photoluminescence spectroscopy (PL) was used to measure the optical properties of ZnO.