I'm trying to anodize Ti foil to grow highly ordered nanotube arrays. I use 0.5 mm thick Ti foil and a grahite counter electrode. The electrolyte is 0.3% wt ammonium flouride and 2% vol distilled water in ethylene glycol. Anodization was done at 60V, for 1h duration.
I would like to know how to clean the foils after anodization. After anodization, my samples have a black deposit on them which peels off when I immerse it in ethanol. I would like to know how to remove the unnecessary precipitates without damaging or peeling off the TiO2 film.
Thank you very much.
You should immediately sonicate your synthesized sample in ethanol for 2 minutes. If ethanol doesn't works and the TNT film peels off, then sonicate in methanol for 2 min. This is what we are doing and it works to clean the debris from the TNT surface.
Another method is, double anodization, where you can sonicate your as grown TNT for 5 min in ethanol and again anodize this Ti foil. So, new TNTs will form from the seeds of previous layer, and it should give uniform debris free TNT arrays.
Use of aged electrolytes (when using ethylene glycol) enables fabrication of mechanically robust nanotubes/nanopores, which will not delaminate if you perform sonication in water or ethanol. Please see some of my papers.
Additionally, we generally avoid sonication and do water rinsing followed by cleaning using UV irradiation. Hope it helps.
Karan Gulati, I have a question, sir. Does water rinsing cause the nanotube layer to peel off?
I am using a two-step anodizing process to fabricate nanotubes, but after 3 hrs of anodizing, the layer peels off just by 35 - 40 seconds of water rinsing!
Mohammad Najari :
Especially when anodizing in organic electrolytes, and when you obtain high aspect ratio nanotubular structures, if you immerse the samples in water, the layers will peel off. This due to the remaining organics in the nanotubes from the organic electrolyte.
When this happens, you can immerse the samples first in ethanol (or methanol, or isopropanol), in order to remove the organic remnants from the anodization electrolyte. The immersion time depends – some prefer 1h or few hours, or overnight. After this, you can wash the nanotubes with water and they should not peel off.
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