Voltage Oscillations and Morphology during the Galvanostatic Formation of Self-Organized TiO2 Nanotubes

The galvanostatic formation of self-organized nanotubular TiO 2 layers on titanium was investigated in 1 M (NH 4 ) 2 SO 4 + 0.5 wt % NH 4 F electrolytes. Under specific electrochemical conditions (anodization above a critical current density) large potential oscillations were observed. The electrochemical and morphological investigations show that these oscillatory phenomena are coupled with sequential growth of the TiO 2 nanotube layer and a subsequent lift-off of these layers. The origin of the detachment process is related to the formation of disordered porous film underneath the first tubular layer at higher voltages. Under galvanostatic conditions that do not lead to lift-off, a nanotubular TiO 2 film with high aspect ratio tubes of medium pore diameter 60 nm and thickness up to 1 μm can be obtained.

[1]  Xingdong Zhang,et al.  Preparation of bioactive titanium metal via anodic oxidation treatment. , 2004, Biomaterials.

[2]  Donal D. C. Bradley,et al.  A solid state solar cell using sol–gel processed material and a polymer , 2001 .

[3]  W. Ingler,et al.  Efficient Photochemical Water Splitting by a Chemically Modified n-TiO2 , 2002, Science.

[4]  Patrik Schmuki,et al.  Thick self-organized porous zirconium oxide formed in H2SO4/NH4F electrolytes , 2004 .

[5]  Jan M. Macak,et al.  Initiation and Growth of Self-Organized TiO2 Nanotubes Anodically Formed in NH4F ∕ ( NH4 ) 2SO4 Electrolytes , 2005 .

[6]  Craig A. Grimes,et al.  Hydrogen sensing using titania nanotubes , 2003 .

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

[8]  V. Parkhutik.  New effects in the kinetics of the electrochemical oxidation of silicon , 2000 .

[9]  Patrik Schmuki,et al.  Self-organized high aspect ratio porous hafnium oxide prepared by electrochemical anodization , 2005 .

[10]  M. Grätzel,et al.  A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films , 1991, Nature.

[11]  V. Parkhutik,et al.  Mechanism of large oscillations of anodic potential during anodization of silicon in H3PO4/HF solutions , 2000 .

[12]  Patrik Schmuki,et al.  Formation of self-organized niobium porous oxide on niobium , 2005 .

[13]  Toshiaki Tamamura,et al.  Highly ordered nanochannel-array architecture in anodic alumina , 1997 .

[14]  Greg P. Smestad,et al.  Characterization of nanocrystalline and thin film TiO2 solar cells with poly(3-undecyl-2,2'-bithiophene) as a sensitizer and hole conductor , 2002 .

[15]  T. C. Downie,et al.  Anodic oxide films on aluminum , 1969 .

[16]  Tadashi Kokubo,et al.  Apatite formation on surfaces of ceramics, metals and polymers in body environment , 1998 .

[17]  Patrik Schmuki,et al.  Self-organized high-aspect-ratio nanoporous zirconium oxides prepared by electrochemical anodization. , 2005, Small.

[18]  Jan M. Macak,et al.  Self-organized porous WO3 formed in NaF electrolytes , 2005 .

[19]  T. Albrektsson,et al.  Characteristics of the surface oxides on turned and electrochemically oxidized pure titanium implants up to dielectric breakdown: the oxide thickness, micropore configurations, surface roughness, crystal structure and chemical composition. , 2002, Biomaterials.

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

[21]  Vitali Parkhutik,et al.  Silicon anodic oxides grown in the oscillatory anodisation regime kinetics of growth, composition and electrical properties , 2001 .

[22]  Patrik Schmuki,et al.  Self-Organized Porous Titanium Oxide Prepared in H 2 SO 4 / HF Electrolytes , 2003 .

[23]  A. Fujishima,et al.  Electrochemical Photolysis of Water at a Semiconductor Electrode , 1972, Nature.

[24]  M. Grätzel.  Dye-sensitized solar cells , 2003 .

[25]  G. Kreisel,et al.  Preparation and characterisation of titanium dioxide films for catalytic applications generated by anodic spark deposition , 2004 .

[26]  Y. Nakato,et al.  Photo-oxidation reaction of water on an n-TiO2 electrode. Improvement in efficiency through formation of surface micropores by photo-etching in H2SO4 , 1995 .

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

[28]  Zhen Ma,et al.  Nanosized anatase TiO2 as precursor for preparation of sulfated titania catalysts , 2002 .

[29]  Patrik Schmuki,et al.  High-aspect-ratio TiO2 nanotubes by anodization of titanium. , 2005, Angewandte Chemie.

[30]  Jan M. Macak,et al.  Self-organized porous titanium oxide prepared in Na2SO4/NaF electrolytes , 2005 .

[31]  Jan M. Macak,et al.  Titanium oxide nanotubes prepared in phosphate electrolytes , 2005 .

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

[33]  John P. Ferraris,et al.  Electrospun mesoporous titanium dioxide fibers , 2004 .

[34]  Kenji Fukuda,et al.  Ordered Metal Nanohole Arrays Made by a Two-Step Replication of Honeycomb Structures of Anodic Alumina , 1995, Science.

[35]  Eugeniu Balaur,et al.  Self-organized TiO2 nanotubes prepared in ammonium fluoride containing acetic acid electrolytes , 2005 .

[36]  R. Asahi,et al.  Visible-Light Photocatalysis in Nitrogen-Doped Titanium Oxides , 2001, Science.

[37]  Eugeniu Balaur,et al.  Tailoring the wettability of TiO2 nanotube layers , 2005 .

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

[39]  Akira Fujishima,et al.  Titanium dioxide photocatalysis , 2000 .

[40]  P. Schmuki,et al.  Self-assembled porous tantalum oxide prepared in H2SO4/HF electrolytes , 2005 .

[41]  R. Hill,et al.  Primary Processes in the Catalytic Photooxidation of p‐Cresol , 1997 .

[42]  Allen J. Bard,et al.  Unassisted water splitting from bipolar Pt/dye-sensitized TiO 2 photoelectrode arrays , 2005 .

[43]  Eiichi Kojima,et al.  Light-induced amphiphilic surfaces , 1997, Nature.

[44]  Frank Müller,et al.  Self-Organized Formation of Hexagonal Pore Structures in Anodic Alumina , 1998 .