Electrochemical tuning of titania nanotube morphology in inhibitor electrolytes

Amrita Centre for Nanosciences, Amrita Institute of Medical Science & Research Centre, Amrita Vishwa Vidyapeetham, Elamakkara P O, Cochin 682 041, Kerala, India
Electrochimica Acta (Impact Factor: 4.09). 04/2010; 55(11):3713. DOI: 10.1016/j.electacta.2009.12.096

ABSTRACT The electrochemical behavior of fluorine containing electrolytes and its influence in controlling the lateral dimensions of TiO(2) nanotubes is thoroughly investigated. Potentiostatic anodization is carried out in three different electrolytes, viz., aqueous hydrofluoric acid (HF), HF containing dimethyl sulphoxide (DMSO) and HF containing ethylene glycol (EG). The experiments were carried out over a broad voltage range from 2 to 200V in 0.1-48 wt% HF concentrations and different electrolytic compositions for anodization times ranging from 5 s to 70 h. The chemistry that dictates how the nature of electrolytes influences the morphology of nanotubes is discussed. Electrochemical impedance spectra were recorded for varying compositions of all the electrolytes. It was observed that composition of the electrolyte and its fluorine inhibiting nature has significant impact on nanotube formation as well as in controlling the aspect ratio. The inhibiting nature of EG is helpful in holding fluorine at the titanium anode, thereby allowing controlled etching at appropriate voltages. Thus our study demonstrates that HF containing EG is a promising electrolytic system providing wide tunability in lateral dimensions and aspect ratio of TiO(2) nanotubes by systematically varying the anodization voltage and electrolyte composition.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Oxygen vacancy (OV) controlled TiO2 nanotubes, having diameters of 50–70 nm and lengths of 200–250 nm, were synthesized by electrochemical anodization in the mixed electrolyte comprising NH4F and ethylene glycol with selective H2O content. The structural evolution of TiO2 nanoforms has been studied by field emission scanning electron microscopy. Variation in the formation of OVs with the variation of the structure of TiO2 nanoforms has been evaluated by photoluminescence and X-ray photoelectron spectroscopy. The sensor characteristics were correlated to the variation of the amount of induced OVs in the nanotubes. The efficient room temperature sensing achieved by the control of OVs of TiO2 nanotube array has paved the way for developing fast responding alcohol sensor with corresponding response magnitude of 60.2%, 45.3%, and 36.5% towards methanol, ethanol, and 2-propanol, respectively.
    Applied Physics Letters 08/2014; 105(8):081604-081604-5. DOI:10.1063/1.4894008
  • [Show abstract] [Hide abstract]
    ABSTRACT: In the present work, well ordered arrays of TiO2 nanotubes were obtained by anodization at different voltages of Ti foil in a solution containing anhydrous ethylene glycol + 0.27 M NH4F and 0.2 wt% water. A detailed study has been performed to evaluate the morphology and electrochemical characteristics of the anodized Ti foil synthesized in different anodization potentials. Correlation between the physical properties and the dimensional aspect of TiO2 nanotubes was examined. In this paper, we report the electrochemical characteristics of the Ti/TiO2 nanotube surfaces from Tafel plots. The electronic properties of TiO2 nanotubular layers were also determined by electrochemical impedance spectroscopy analysis (EIS). EIS is considered to be a valuable tool that allows determining barrier oxide parameters. A linear dependence of barrier thickness on the anodizing voltage was verified from 20 to 50 V, the proportionality constant of the barrier layer thickness in relation to the applied anodizing voltage was estimated from the proposed equivalent circuit.
    Journal of The Electrochemical Society 01/2012; 159(4):K83. DOI:10.1149/2.077204jes
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Titania (TiO2) nanotube arrays (TNAs) with different pore diameters (140 - 20 nm) are fabricated via anodization using hydrofluoric acid (HF) containing ethylene glycol (EG) by changing the HF-to-EG volume ratio and the anodization voltage. To evaluate the effects of different pore diameters of TiO2 nanotubes on bacterial biofilm formation, Shewanella oneidensis (S. oneidensis) MR-1 cells and a crystal-violet biofilm assay are used. The surface roughness and wettability of the TNA surfaces as a function of pore diameter, measured via the contact angle and AFM techniques, are correlated with the controlled biofilm formation. Biofilm formation increases with the decreasing nanotube pore diameter, and a 20 nm TiO2 nanotube shows the maximum biofilm formation. The measurements revealed that 20 nm surfaces have the least hydrophilicity with the highest surface roughness of ∼17 nm and that they show almost a 90% increase in the effective surface area relative to the 140 nm TNAs, which stimulate the cells more effectively to produce the pili to attach to the surface for more biofilm formation. The results demonstrate that bacterial cell adhesion (and hence, biofilm formation) can effectively be controlled by tuning the roughness and wettability of TNAs via controlling the pore diameters of TNA surfaces. This biofilm formation as a function of the surface properties of TNAs can be a potential candidate for both medical applications and as electrodes in microbial fuel cells.
    Nanotechnology 10/2014; 26(6). DOI:10.1088/0957-4484/26/6/065102


Available from
Sep 23, 2014