Sequential Synthesis of Cu-Copper Sulfide Heterostructure Nanocrystals and Copper Sulfide Nanocages
Y. Liu, A.R. Hight Walker
National Institute of Standards and Technology (NIST), US
Keywords: Cu-Copper sulfide, heterostructure, nanocages
Abstract:Heterostructure nanocrystals (HNCs), also called hybrid nanocrystals, are nanocrystals of different materials interconnected through epitaxial interfaces. These HNCs with multifunctional entities provide a much higher technology potential over conventional nanocrystals. On the other hand, nanocages, referring to hollow, porous nanocrystals have been extensively investigated in the fields of catalysis, solar cells, drug delivery, and so on. The synthesis of both HNCs and nanocages in terms of size- and shape-control remains a challenging task. For the first time, we present the sequential formation of Cu-copper sulfide hetero-oligomers HNCs and copper sulfide nanocages following one facile, two-step reaction mechanism in an organic solution. The synthesis has been performed under a unique surfactant environment, involving the initial production of Cu nanoparticles (NPs) as templates, the subsequent heterogeneous growth of copper sulfide on Cu NPs, and the eventual formation of nanocages. It has been found that the starting shapes of Cu NPs have significant effect on the structures of Cu-copper sulfide HNCs. For instance, well-defined crystalline Cu NPs often lead to symmetrical structures of HNCs, while defective Cu NPs precursors produce irregular HNCs. The as-prepared nanostructures are characterized using TEM, HR-TEM, XRD, and UV-visible spectroscopy. The time-dependent growth studies on copper sulfide and formation mechanism of both HNCs and nanocages will also be discussed.