I'm trying to prepare TiO2 nanotubes by anodizing Ti metal.
Electrolye is 0.5 M H2SO4 and 0.5% HF and cathode is SUS.
Anodization for TiO2 nanotube synthesis usually takes about 2 h.
And it is annealed at 450 oC for 1 h in air.
Nanotube arrays are formed but sometimes not...
What are the problems?
Could you show me the photos of TiO2 nanotube (taken by phone camera..) before and after thermal annealing because I want to see colors ...?
Thank you.
You can try another synthetic method which uses Ethylene glycol as eletrolyte, NH4F, and around 2 volume percent DI water. There are many papers on this method. You will get reproducible results.
Yes, try ethylene glycol based electrolytes. See some of my papers.
Generally, after anodization the nanotubes will be brown in color and after annealing it will be darkened a bit (and the underlying Titanium will develop a bluish color).
Dear Mj,
Use another method. Now ammonium fluoride +glycerol + ethylene glycol is best option you can have. You can use organic electrolyte which may result you better in finding crystalline phase.
According to the process of anodization, the applied voltage, duration time, and water content in electrolyte are the key factors when fabricating TiO2 nanotubes. In organic electrolyte containing EG, the long nanotubes with high aspect ratio are generally obtained.
Process
Collect titanium foil and first clean ultrasonically in acetone and deionized water. Than anodize in glycerol (85%, Merck) containing 6 wt% ethylene glycol (Merck) and 5 wt% ammonium fluoride (Merck); the glycerol used here may contained 15% water. Use different voltages range 20-60 V up to net 60 min. To study the effect of the optimal voltage for growing TiO2 nanotubes maintain anodization time (it may be 20-200 minute). Sample rinse with deionized water and dry in air. Titanium is anodized. Now Anodized Ti must anneal at 400 to 700 °C for 2 h in argon to obtain the crystalline phase. Another set of experiments can be performed to investigate the effect of the cathode material on the formation of TiO2 nanotubes.
Ashish
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