Carbon nanotubes (fuel cell catalyst support)

[aldogago]

First of all, I thank you Stefan for inviting me to your forum. About your question if carbon nanotubes (CNT) conduct electricity like graphite, they do, but just as a bulk material. They show very peculiar electric properties at nanosized scale, since electronic conduction occurs on the CNT surface. Right now its been researching their capabilities for using them as transistors, supercapacitors, and field emission cathodes in TV displays, just to mention a few applications due to the their electric properties that other forms of carbon (graphite) don?t have.

At the Research Center for Advanced Materials (CIMAV), where I?m doing my postgraduate research, we study CNT as electrocatalyst support for polymer electrolyte membrane fuel cell (PEMFC), PEM electrolysers, and foto-electrocatalysis cells electrodes. All of those applications are related with hydrogen utilization and/or hydrogen production. We use colloidal methods to synthesize and deposit electrocatalyts nanoparticles on the CNT surface and then we perform electrochemical tests under similar conditions as they occur in fuel cells. All of this with the purpose of studying and compare their performance with the carbon commonly used in fuel cells.

About your question of how do we produce the CNT, well? we use the spray pyrolysis method which is a kind of variation of the popular chemical vapor deposition (CVD) technique. This method consists in passing a flow of argon gas mixed with ferrocene/toluene small droplets, into a high temperature (900?C) quartz tube. The ferrum from the ferrocene acts as a catalyst and the CNT grows on the metal surface. When the whole process is finished, and after the quartz tube is cold enough (room temperature), we remove the black soot deposited inside the tube and that is a large quantity (several grams) of multiwalled carbon nanotubes (MWCNT). I?ve already uploaded a new video in my channel at youtube about this method:

http://www.youtube.com/watch?v=Z0h1N3IFOdI

In fact, it is an old video since right now I?m working in a project of how to improve the process for producing CNT at industrial scale (at least several hundreds of grams).

I?ll be continuing visiting this forum to try to answer any questions you have related to the CNT research that we are doing, or please visit my channel in youtube and post your comments about my videos.

Thanks,

Aldo

[hartiberlin]

Hi Aldo,
many thanks for this interesting infos.
Is there also any easy chemical process to produce conducting graphite (not just only CNTs) at home from some kind of  fluids you put together and have conducting graphite as the output ?

2.if I use 2 conductive graphite rods or plates in a water-NaCl solution,I can charge this cell up
like a supercap via DC voltage.
Now is it possible to use also Hydrogen and Oxygen to charge up the graphite electrodes and thus get a cheap fuel cell?
Or do I need expensive catalysts for this ?
Does that work without Platin with CNTs ?
Many thanks.

[hartiberlin]

Here is a page, that shows how to build a simple fuel cell from platin wire:

http://scienceathome.cienciaviva.pt/celcombsalina_eng.html

but if you use graphite rods or plates you can store much more power in it,
cause during the electrolysis the graphite will suck in the gases or ions..

The problem is, that just feeding hydrogen and oxygen gas alone
to the graphitre rods does not produce any significant power, so I assume
that the graphite needs the ions not the pure gas in its lattice....

Do we really need platin doped or electroplated onto the graphite
to break the gas apart into ions to get a good efficiency fuel cell ?
That is the main question... ! ?

[hartiberlin]

P.S. Aldo,
the only way I know of to make cheaply conductive graphite with homemade
materials is this:

http://www.overunity.com/index.php/topic,790.0.html

It needs pressed coal brikets and letting it glow red hot,
so the carbon transforms to conductive graphite, but surely
these are no small Nanotubes..