Dear All,
I want to functionalize my CNTs to use in electrochemical bio-sensors .I would be grateful if you kindly let me know about :
1. Which acids and how much? (Phosphoric acid , Nitric acid , Sulfuric acid )
2.how to drop the acids on the substrate ?using simple dropping or I have to use spin coating to be uniform?
3.how long I have to put the CNTs in the solution?(My sample is vertical CNTs)
4.how about the temperature and PH of the process ?
5.If I used acids and open the -COOH bands, Do I have to immediately use it?I mean after treating with acids I can storage it or not?
Personal Regards
Amin
You have to treat CNTs with nitric acid, details can be found at my published article; MODIFICATION AND FUNCTIONALIZATION OF MULTIWALLED CARBON NANOTUBE (MWCNT) VIA FISCHER ESTERIFICATION, The Arabian Journal for Science and Engineering, Volume 35, Number 1C
You have to treat CNTs with H2SO4/HNO3 mixture by 3:1 . This mixture heated in 70 C for 4 Hr. and then neutralized by NaOH.
Hello,
1. H2SO4/HNO3 (3:1) as Ali Ashraf told you, it is the most common. H2SO4/H2O2 (2:1) is very effective too (but be carefull, it could be dangerous).
2. The normal way is not dropping acids on CNTs. The CNTs functionalization with oxidative acids is refluxing. You say in (3) that it is vertical CNTs so the best solution would be dipping the CNTs in the acids solution and heat.
3. 2 hours 80ºC could be enough. It depends on the grade of CNTs’ oxidation that you desire. I thing that there is a relation between time and functionalization grade (may be a Gooding paper in 2005…I don’t remember exactly).
4. The normal procedures are 70ºC and high. pH is not adecuate in this case, it is a mixture of concentrated acids.
5. I think that the COOH groups are stable enough because there are commercial CNT functionalized. A small time-evolution of the CNTs groups could be possible although I will not be worry about it for biosensor applications.
On the other hand, have you think about a O2 plasma treatment? It could be useful for your case.
Hi! The best ratio of the acids is H2SO4:HNO3 (3:1).
The whole method is described to the experimental method of the paper below.
http://www.sciencedirect.com/science/article/pii/S0927024809003390
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