Dear Eleonora

Try to carry on the gold deposit on a set of fresh /new carbon fibers without the pretreatment.

Or try to preserve the pretreated carbon fibers in a day chamber ,then after a period of time deposit the gold.

I will simply carboxylate the fibers in nitric acid and add aptms prior to the gold deposition

Hi Eleonora,

carbon fibers typically have a polymer sizing to improve processibility in textile processing, which has to be removed. Un-sized fibers are not easily available if you buy them they always have the sizing.

Typically the sizing comes off at 700-800°C in flowing nitrogen without affecting the surface properties.

Some of the sizings can be washed off by repeated rinsing treatment (ultrasonic) with acetone (thats the easy way but typically leaves a small residue whatever you do).

Oxydation either wet chemical (see Joydeep's contribution) or by a bunsen flame (thats what we did in the early 1990s) is the brute force method. It may also change the surface chemistry quite a bit which may promote adhesion.

Frank

Google for "gold adhesion carbon," "gold adhesion polymers," "electrochemical gold carbon," and similar key words to find numerous papers published by people who've done related work over the years, then try some of the techniques described by them.

Frank Kern Joydeep Dutta thank you for your replies, I will try what you suggested. I thought the problem could have been some sort of protective polymer.

Khaled J. Habib thank you. Unfortunately I don't have fresh/new carbon fibres to use at the moment. The spool I have was opened several months ago. Might be slightly contaminated.

Valery Ray thank you. I have done plenty of research on Google Scholar, but I haven't found much about the pre-treatment prior deposition. There is a lot about how to deposit gold on carbon, but not a lot about how to clean the fibres. This is why I asked my question.

Hi Eleonora,

I agree with Frank Kern , epoxy sizing on the carbon fiber might be hindering the deposition of gold nanoparticles on its surface.

Apart from what Frank Kern suggested, you can also use Oxygen / Nitrogen plasma (If you have access to it ), The epoxy sizing will be etched (you can clearly see that in AFM as well ) and it will also increase some disorder in the graphitic carbon structure of carbon fiber which might help in the sticking of the gold nanopartciles.

All the best !!

Frank Kern for how long should I keep the fibres at that temperature in nitrogen atmosphere? Thank you in advance.

As per my knowledge please perform the suggested process for better results:

1. Firstly clean with acetone ethanol solution (1:1 ratio), then oven dried at 90 degree Celsius for 25 minutes.

2. Now dip the samples in 10% NaOH solution for 20 min then rinse with deionized water several times then dry the samples at 90 C for 1 hour.

3. finally soaked the samples in HCl (10 N ) solution for 10 seconds only then wash with distilled water and oven dried for 2 hrs at 90 degree.

i hope this will help in your work, all the best.