Fabrication of tapered, conical-shaped titania nanotubes

Using anodic oxidation with a time-dependent linearly varying anodization voltage, we have made films of tapered, conical-shaped titania nanotubes. The tapered, conical-shaped nanotubes were obtained by anodizing titanium foil in a 0.5% hydrofluoric acid electrolyte, with the anodization voltage linearly increased from 10-23 V at rates varying from 2.0-0.43 V/min. The linearly increasing anodization voltage results in a linearly increasing nanotube diameter, with the outcome being an array of conical-shaped nanotubes approximately 500 nm in length. Evidence provided by scanning electron-microscope images of the titanium substrate during the initial stages of the anodization process enabled us to propose a mechanism of nanotube formation.

[1]  V. Parkhutik,et al.  Theoretical modelling of porous oxide growth on aluminium , 1992 .

[2]  Yoshio Bando,et al.  Sol-gel template preparation of TiO2 nanotubes and nanorods , 2001 .

[3]  J. Delplancke,et al.  Galvanostatic anodization of titanium—II. Reactions efficiencies and electrochemical behaviour model , 1988 .

[4]  G. Patermarakis,et al.  Mathematical models for the anodization conditions and structural features of porous anodic Al{sub 2}O{sub 3} films on aluminum , 1995 .

[5]  Tohru Sekino,et al.  Titania Nanotubes Prepared by Chemical Processing , 1999 .

[6]  G. Thompson,et al.  Development of porous anodic films on 2014-T4 aluminium alloy in tetraborate electrolyte , 2003 .

[7]  Kornelius Nielsch,et al.  Hexagonal pore arrays with a 50-420 nm interpore distance formed by self-organization in anodic alumina , 1998 .

[8]  G. C. Wood,et al.  The anodizing of aluminium in sulphate solutions , 1970 .

[9]  M. Yoshimura,et al.  The electrochemical behavior and characterization of the anodic oxide film formed on titanium in NaOH solutions , 2002 .

[10]  K. Jonas.  Der Einfluß der Zerkleinerung von Zellstoff auf die Kupferzahl , 1928 .

[11]  Ralf B. Wehrspohn,et al.  Hexagonally Arranged Monodisperse Silver Nanowires with Adjustable Diameter and High Aspect Ratio , 2003 .

[12]  K. G. Ong,et al.  Highly Ordered Nanoporous Alumina Films: Effect of Pore Size and Uniformity on Sensing Performance , 2002 .

[13]  T Albrektsson,et al.  The electrochemical oxide growth behaviour on titanium in acid and alkaline electrolytes. , 2001, Medical engineering & physics.

[14]  G. L. Sharma,et al.  High ethanol sensitivity in sol–gel derived SnO2 thin films , 1999 .

[15]  Craig A. Grimes,et al.  Crystallization and high-temperature structural stability of titanium oxide nanotube arrays , 2003 .

[16]  P. Lenas,et al.  Kinetics of growth of porous anodic Al2O3 films on A1 metal , 1991 .

[17]  Shahed U. M. Khan,et al.  Photoresponse of n-TiO2 thin film and nanowire electrodes , 2003 .

[18]  Craig A. Grimes,et al.  Room Temperature Ammonia and Humidity Sensing Using Highly Ordered Nanoporous Alumina Films , 2002 .

[19]  Tae Jae Lee,et al.  Field emission from well-aligned zinc oxide nanowires grown at low temperature , 2002 .

[20]  W. Brown,et al.  Alkyltrimethylammonium Bromide Adsorption on Polystyrene Latex Particles Studied by Dynamic Light Scattering and Adsorption Isotherms: Effects of the Surface Polymer Layer and Modified Aromatic Amino Groups , 1996 .

[21]  Marc Aucouturier,et al.  Anodic oxidation of titanium and TA6V alloy in chromic media. An electrochemical approach , 1999 .

[22]  Jackie Y. Ying,et al.  Defect and transport properties of nanocrystalline CeO2-x , 1996 .

[23]  B. Hwang,et al.  Kinetic model of anodic oxidation of titanium in sulphuric acid , 1993 .

[24]  D. Macdonald.  On the Formation of Voids in Anodic Oxide Films on Aluminum , 1993 .

[25]  M Ferrari,et al.  Micromachined interfaces: new approaches in cell immunoisolation and biomolecular separation. , 2000, Biomolecular engineering.

[26]  J. Siejka,et al.  An O18 Study of Field‐Assisted Pore Formation in Compact Anodic Oxide Films on Aluminum , 1977 .

[27]  Craig A. Grimes,et al.  Extreme Changes in the Electrical Resistance of Titania Nanotubes with Hydrogen Exposure , 2003 .

[28]  Marc Aucouturier,et al.  Structure and physicochemistry of anodic oxide films on titanium and TA6V alloy , 1999 .

[29]  H. Imai,et al.  Direct preparation of anatase TiO2 nanotubes in porous alumina membranes , 1999 .

[30]  T. C. Downie,et al.  The dissolution of porous oxide films on aluminium , 1970 .

[31]  Craig A. Grimes,et al.  Titanium oxide nanotube arrays prepared by anodic oxidation , 2001 .

[32]  G. Patermarakis,et al.  The mechanism of growth of porous anodic Al2O3 films on aluminium at high film thicknesses , 1995 .

[33]  P. Hoyer,et al.  Formation of a Titanium Dioxide Nanotube Array , 1996 .

[34]  Qing Chen,et al.  Trititanate nanotubes made via a single alkali treatment , 2002 .

[35]  G. Stucky,et al.  Sensitized luminescence of trivalent europium by three-dimensionally arranged anatase nanocrystals in mesostructured titania thin films. , 2002, Angewandte Chemie.

[36]  Jaesung Song,et al.  Photocatalytic Characteristics of Nanometer‐Sized Titania Powders Fabricated by a Homogeneous‐Precipitation Process , 2004 .

[37]  Frank Müller,et al.  Self-organized formation of hexagonal pore arrays in anodic alumina , 1998 .

[38]  G. Thompson,et al.  Porous anodic alumina: fabrication, characterization and applications , 1997 .