Abstract: This work describes the electrochemical synthesis of cadmium sulfide (CdS) nanostructured films by applying a pulsed current technique on the gold electrode modified with a self-assembled p-aminothiophenol monolayer (PATP/Au). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the morphology and crystal phase of the synthesized samples. An ordered array of CdS nanorods with a relatively higher c-axis preferred orientation was found on the PATP/ Au substrate. The results indicated that the size of the CdS nanorods increased with the increase in the pulse width of the pulsed current, whereas the uniformity decreased. Furthermore, the size and coverage of the CdS nanorods increased with the increase in the pulse height. Thus, the morphology and size of the prepared CdS nanorods could be controlled by adjusting the pulse width and height. Cyclic voltammetry (CV) and chronopotentiometry were also applied to investigate the mechanism of the electrodeposition of CdS on PATP/Au. In accordance with the experimental results, we suggest that the interaction of the －NH₂ in PATP molecules with Cd²⁺ in the solution may have contributed to the passing of electrons along the PATP chain following a modification of the p-aminothiophenol monolayer on the Au substrate. A formation mechanism for the electrochemically synthesized CdS nanorods on the PATP/Au substrate has consequently been proposed.

Key words: Pulsed current technique, Cadmium sulfide, p-Aminothiophenol, Morphology control, Nanostructured film, Nanorod