Atomic layer deposition of TiO2 nanotubes and its improved electrostatic capacitance

Titanium dioxide (TiO2) nanotubes are fabricated into anodic aluminum oxide (AAO) membrane via atomic layer deposition (ALD). For the ALD of TiO2, gaseous precursors, titanium (IV) isopropoxide and water are sequentially applied and chemically reacted with each other. A thickness of nanotubes is precisely controlled by the applied cycle numbers of ALD and the morphology of nanostructures is investigated by SEM and TEM. The amorphous property of TiO2 nanostructures is revealed by XRD and the composition of nanotubes is measured by TEM-EDX. The impurity contents and binding structure of the nanostructures are analyzed by XPS. The electrostatic capacitance of TiO2 nanotubes into AAO is 480 mu F/cm(2) and it is about 3 times higher compared with AAO membrane (172 mu F/cm(2)). (C) 2009 Elsevier B.V. All rights reserved.