Fabrication of ordered SnO2 nanotube arrays via a template route

Ordered stannic oxide nanotube arrays are fabricated by a sol–gel approach employing porous anodic alumina (PAA) membranes as the template. Polycrystalline SnO2 nanotubes with well-defined composition are obtained. Electron microscopy images indicate that the SnO2 nanotubes are well assembled and parallel to each other in the pores, with the outer diameter matching well with the pore diameter. The thickness of the wall is estimated to be 20 nm. X-ray diffraction and select area electron diffraction as well as high-resolution transition electron diffraction demonstrate that the structure of the nanotubes can be indexed to rutile phase SnO2. The formation mechanism of the tubular morphology is also discussed.