Large-scale controlled synthesis of silica nanotubes using zinc oxide nanowires as templates

We report on the controlled synthesis of silica nanotubes on a large scale using ZnO nanowires as templates. The ZnO nanowires are first coated with a uniform silica layer by a sol–gel method. Then silica nanotubes are obtained after removal of ZnO nanowires in diluted hydrochloric acid solution. The thickness of the outer walls is tuned from ∼5 to ∼30 nm and the inner diameter is completely dependent on the size of the ZnO nanowires. Moreover, three-dimensional nanotubes such as tetrapod-like silica nanotubes are also synthesized through the same approach. Silica nanotubes with various thicknesses of outer walls and with special morphologies are expected to have potential applications in designing and fabricating novel nanodevices.