Fabrication and Characterization of Highly-Ordered Valve-Metal Oxide Nanotubes and Their Derivative

Highly ordered and vertically aligned straight nanotubes can be fabricated using an electrochemical anodization method on the valve metal surfaces, and a variety of nanostructures can be derived from these nanotubes. These nanomaterials have found a wide range of applications, especially in the fields of renewable energy gen-eration and storage. This review provides step-by-step guidelines about the fabrication details and parameters of these nanomaterials, focusing on the systems originated from the metals of Al, Ti and Zr. Based on the fabrication of these nanotubes, different methods were developed to produce uniform metal nanowires using electrodeposition and mechanical injection, nanospheres and nanowhiskers on the top surfaces of the nano-tubes, and dye-sensitized solar cells using anodic Ti oxide. These nanostructures and their phase transitions were characterized in detail by X-ray diffraction and electron microscopy techniques. Finally, towards the com