Tuning the Morphology of Au/CdS Nanocomposites through Temperature-Controlled Reduction of Gold-Oleate Complexes

A general synthetic strategy for controlling the shape of gold domains grown onto CdS semiconductor nanocrystals is presented. The colloidal growth of Au nanoparticles is based on the temperature-controlled reduction of Au-oleate complexes on the surface of CdS and allows for precise tuning of nanoparticle diameters from 2.5 to 16 nm simply by adjusting the temperature of the growth solution, whereas the shape of Au/CdS nanocomposites can be controllably switched between matchsticks and barbells via the reaction rate. Depending on the exact morphology of Au and CdS domains, fabricated nanocomposites can undergo evaporation-induced self-assembly on a substrate either through end-to-end coupling of Au domains, resulting in the formation of one-dimensional chains or via side-by-side packing of CdS nanorods, leading to the onset of two-dimensional superlattices.