Understanding and Controlling the Growth of Monodisperse CdS Nanowires in Solution

Abstract

Cadmium sulfide (CdS) nanowires with a monodisperse diameter of 3.5 nm and length of about 600 nm were successfully synthesized using a simple and reproducible hot coordination solvents method. Structural characterization showed that the one-dimensional nanowires grow along the [001] direction and have the wurtzite structure. The morphology of the nanocrystals is affected by the octadecylphosphonic acid to cadmium (ODPA-to-Cd) mole ratio, the precursor ratio (Cd-to-S mole ratio), the precursor concentration, the precursor injection process, and the type of ligands used in the synthesis. However, we propose that the ODPA-to-Cd mole ratio is the key factor affecting the morphology of the nanowires because it affects both the cleavage rate of the P═S double bond and the nucleation/growth rate of the anisotropic nanocrystals. In addition, it was found that Cd−ODPA complexes give rise to a low diffusion rate of the precursor and hence low reactivity. Therefore, ODPA is good for generating nearly monodisperse a...