The formation mechanism of titania nanotube arrays in hydrofluoric acid electrolyte
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Self-organized and highly ordered titania nanotube arrays (TNAs) were prepared through electrochemical anodic oxidization on a titanium foil in 0.5 wt.% hydrofluoric acid (HF) electrolyte. The current density and morphology images during the formation process of TNAs were studied. Results show that the formation of TNAs includes the following processes. Initially, dense oxide of titania was rapidly formed on the titanium surface, followed by small pore formation. The adjacent small pores were then integrated and become larger pores. At the same time, small tubes were transformed. These small tubes were further integrated into larger tubes until the primary tube formation. Finally, the tubular structure was gradually optimized and eventually developed into the highly ordered TNAs. A model was proposed to explain the formation mechanism of TNAs fabricated on a titanium foil in HF acid electrolyte.
KeywordsTubular Structure Anodization Voltage Small Tube Titanium Foil Dense Oxide
This work was supported by the National Nature Science Foundation of China (No. 20677039), Science and Technology Commission of Shanghai Municipality (No. 05nm05004) and the Program of New Century Excellent Talents in University (No. NCET-04-0406). Thanks for support of FE-SEM lab in Instrumental Analysis Center of SJTU.