Morphological Evolution of CdS Nanowires to Nanosheets

We report on the formation mechanism of CdS nanosheets based upon extensive scanning electron microscopy and transmission electron microscopy experiments. Two different CdS nanowires were synthesized, whose axial directions are in parallel with [0001] or [01̄10]. The [0001]-nanowires sustained one-dimensional growth characteristics irrespective of reaction temperature and duration. On the other hand, we observed two-dimensional lateral growth in the [01̄10]-nanowires. We proposed a three-step process for the morphological evolution of CdS nanowires to nanosheets; (1) nucleation and growth of nanowires by vapor-liquid-solid mechanism, (2) side-branching of secondary nanowires perpendicular to the original nanowires and filling between them by vapor-solid mechanism, and finally (3) formation of nanosheets through the repetition of side-branching and filling processes.