Synthesis of ZnO whiskers via EDTA-assisted hydrothermal routes

Uniform ZnO whiskers with a length of 3.5–4.0 μm and a diameter of 180 nm have been synthesised via the EDTA–assisted hydrothermal route, using ZnO nanoparticles as the raw material and NaOH solution as the reaction medium. In order to convert the ZnO nanoparticles to ZnO whiskers via the dissolution–hydrothermal precipitation route, ZnO nanoparticles were firstly dissolved in concentrated NaOH solutions at room temperature and then diluted with water to form the super–saturated meta–stable solution before hydrothermal treatment. The presence of minor amount of EDTA favoured the 1D growth of ZnO whiskers. The possible growth mechanism of ZnO whiskers and the effect of EDTA were discussed from the viewpoint of thermodynamic analysis.