UC Riverside

Nanostructured materials have attracted extensive attention due to their small dimension and enhanced properties compared to bulk materials, and their large range of potential applications in energy harvesting devices. Among these materials, nanostructured chalcogenides play an important role in thermoelectric and solar cell devices. Electrochemical techniques have drawn attention as an improved method for synthesizing nanostructured chalcogenide materials, since they provide a cost-effective, simple, and versatile method for depositing various kind of chalcogenides with tunable nanostructures and properties.

The overall objective of this dissertation work is to develop the following electrochemical techniques:

1) to synthesize nanostructured chalcogenide materials (e.g. Bi_xTe_y, Pb_xTe_y and Cd_xTe_y) with well-controlled dimensions, surface morphologies and compositions

2) to systematically investigate the effect of experimental parameters on their nanostructures

3) to characterize their tunable properties

4) and ultimately to establish a guidance of experimental design for further synthesis of other nanostructured chalcogenide materials.

In this dissertation, the viability of using electrochemical methods for synthesizing nanostructured three chalcogenide materials - Bismuth telluride (Bi_xTe_y) Lead telluride (Pb_xTe_y) and Cadmium telluride (Cd_xTe_y) was tested. An easy way to tune their size (nano to micro), surface morphology (from novel nanostructures to nanoparticles and core/shell hybrid nanostructure) and composition (excess either electropositive element or chalcogens) by tailoring the electrochemical parameters such as electrolyte composition, type and thickness of sacrificial materials, and reaction time of electrochemical techniques, including electrodeposition (ED) and galvanic displacement (GD), was demonstrated.