Synthesis of TiO₂ and CuO Nanotubes and Nanowires

Nanowires, nanotubes, nanobelts, nanoribbons, nanorods etc. are a new class of quasi-one-dimensional materials that have been attracting a great research interest since last few years. In the words of David Appell "Nanowires, nanorods or nanowhiskers. It doesn't matter what you call them, they're the hottest property in nanotechnology." These nanomaterials have been proposed as important components of electronic and optoelectronic nanodevices and are expected to play an integral part in the design and construction of these devices. Among these nanostructures, compound semiconductor nanowires and nanotubes are attracting more and more attention due to their great potential applications in nanodevices. Apart from ZnO, TiO₂ and CuO semiconductors have attracted considerable attentions due to their wide applications in enormous area of research. Titanium dioxide, due to its specific semiconductive properties, has been a highly investigated material for a plethora of applications, such as solar cells, photocatalysis, hydrogen production, self-cleaning coatings or purification of water and air. Simileraly As a p-type semiconductor with a narrow bandgap (1.4 eV), CuO has been extensively studied because an important component of copper oxide superconductors, a powerful heterogeneous catalyst, magnetic storage media, solar energy transformation, field emission and gas sensors. Due to their high aspect ratio one dimensional nanomaterials of these oxides have a superior property in all related areas. Various methods have been adopted for the synthesis of one dimensional nanowires and nanotubes of TiO₂ and CuO. Among these electrochemical based anodization for TiO₂ nanotubes and copper based thermal oxidation for CuO nanowires have been widely studied. This review covers various synthetic strategies adopted so far, for the synthesis of TiO₂ and CuO nanotubes and nanowires.