I have run into similar issues using porous hydrofillic carbon papers. Usually we found that wrapping self-adhesive Teflon tape around the sample above the exposed area prevented this issue. If this is not enough for your system, you may be able to drop water dispersed Teflon polymer (or colorless nail polish) onto your eletrode above your active area. After drying this makes an impenetrable and inert barrier.

Thanks Mr Laursen,

I've also tried wrapping adhesive tape but doesn't seem to work well. Maybe the nail polish or PTFE might help! I don't have PTFE but I think PVDF will work too.

Thanks again

Hi John, if the Teflon thing does not work well you could do these things as follows. First, you can use PVDF as a binder for your free-standing fiber containing film with the desired substrate. Otherwise some kind of conducting carbon pest is also available which you could try. Another thing is the triton x100 non-ionic surfactant. You could try with this also. If not, then deposit the fiber mats (very dense fiber mat which cloud serve the purpose of the free standing mat) directly on conducting substrates- like conducting Si-wafers, or metals or carbon papers, graphite blocks.

My suggestion is to use Kapton adhesive tape which is stable in almost all solvents.I have used this for masking carbon paper during electro-deposition of PEDOT in acetonitrile it works well for me.

Dear John I have also plan to make free standing PAN films. But it is not coming well fro me. Can you help me in this regard.

Dear John

First of all could you please clarify what material are you using as your working electrode. Since you prepared "PAN composite nanofibers, followed by stabilization and carbonization" I believe you don't have PAN anymore but mainly your inorganic phase ... probably too fragile to be handled with any kind of tape.

Dear José,

Yup, should be called carbon nanofibers, well, it's not purely all inorganic phase because I still have the carbon backbone due to carbonization in inert atmosphere. If it's done in air then what's left behind are mostly inorganic compounds, where it will be too brittle and it needs binder and carbon black to be used as an electrode.

Dear Bihag,

I think the most tricky part is the thermal treatment of PAN. Make sure it's stabilized around 250-280 at 1C/min in air and then followed by carbonization at 800-1000 at 5C/min in inert atmosphere. How did you obtain the film?

Thanks John. Flow rate is it important or the atmosphere will be sufficient .?

I didn't got the free standing films its film on aluminium substrate.

I'm not sure, but I did it in a continuous flow rate around 80sccm