Formation of Self Ordered TiO_2 Nanotubes by Electrochemical Anodization of Titanium in 2-Propanol/NH_4F

摘要

In the present work we report that TiO_2 nanotubes (TiNT) can be formed by electrochemical anodization of titanium in an 2-propanol/water+0.14M NH_4F. The effects of water contents, time of anodization and the potential on the growth behavior of the TiNT were studied. The optimum solvent composition of water/2-propanol was found 16vol% water. At this % the reaction between solvated electrons and hydrogen ions, which was considered as a possible rate-determining step, is kinetically controlled. The titania nanotubes obtained under the optimum conditions have heights up to 1800nm and inner diameters around 90nm. Increasing the potential beyond 20V did not show better nanotubes. This was attributed to the fast reactions under the high field led to disordering equilibrium of the controlling reactions.