Generalized Solution Synthesis of Large Arrays of Extended and Oriented Nanowires

Recently rational design and synthesis of extended and oriented nanostructures, such as oriented carbon nanotubes, semiconducting nanowires, oriented oxides, and metals have attracted wide attention. Nanostructured films made of oriented nanorods and high surface area architectures are desirable for many applications, including microelectronic devices, chemical and biological sensing and diagnosis, energy conversion and storage (photovoltaic cells, batteries and capacitors, and hydrogen storage devices), light emitting display devices, catalysis, drug delivery, separation, and optical storage. Many methods have been reported for the preparation of oriented nanostructures. For example, chemical vapor deposition is a widely used method to prepare oriented carbon nanotubes [1, 2], nanorods of ZnO [3, 4], Si [5], silicon carbide/nitride [6], and nanobelts of a wide range of oxide materials [7]. Besides the high temperature approach, a solution based synthesis method has been developed to prepare oriented nanorods of ZnO using a hydrothermal process [8, 9]. Oriented iron oxide nanorods were also prepared through the solution method by controlling the nucleation and growth of the minerals [10].