DIY Synthesis of carbon nanofibers from atmospheric CO2

I finally managed to do the initial carbon nanofiber experiments during July!

Just to heat the empty crucible to 730°C and keep the temperature there took me 15 trial-and-error iterations. I settled on induction heating, a steel pot on rock wool and ceramic chopsticks through which a fan contraption blew air through…

I even made a video out of one experiment.

A friend at a research institute was helpful enough to take a couple of SEM pictures of the resulting washed cathode product:

CNF-Sample 220160627.000001

CNF-Sample 220160627.000002

CNF-Sample 220160627.000003

The pictures show curled up, around 1μm thick fibers similar to the ones published in the supplement for the “One-Pot Synthesis of Carbon Nanofibers from CO2” -paper that I used as a reference, where the electrolyte had had a lot of iron in it. This makes sense as I had used a steel pot instead of an alumina crucible…

Other things to try next time would be to bubble air into the electrolyte (lowers the concentration of lithium oxide), use cathodes with thicker surface layer of zinc and/or increase the duration of the initial low current step.

I hope I get the chance to soon experiment a bit more!

Update:
Here’s something about a new experiments.

4 thoughts on “DIY Synthesis of carbon nanofibers from atmospheric CO2

  1. Santosh Manivannan

    I have a few questions:
    1) What happens to the lithium carbonate after the experiment? i mean is it reusable?
    2) How pure is the carbon produced by this?

    • oknuutti Post author

      Thank you for your interest! The lithium carbonate would remain reusable if enough co2 can be absorbed by the surface of the molten lithium carbonate. If that is impractical, would need to bubble air (or concentrated co2) through the liquid. The carbon is mixed with lithium carbonate and nickel. Lithium carbonate is weakly soluble in water, so theoretically you could wash it away with water. However, it’s very slow. Using a weak acid works faster. If you use a strong enough acid, then can get rid of most of the nickel also. Nanofiber content is a bit harder question as I still don’t have results from the second set of experiments. First experiments were most likely ruined in this sense because of too much iron in the solution.

  2. Will

    Have you thought about using a nickel crucible as the anode?

    • oknuutti Post author

      You’re right, nickel crucible would be something to try out and I did consider it for the next experiment. However, as the article I based this experiment on suggested in one section that a small nickel anode would help getting thin straight fibers – and the results I got from the first experiment was thick, curled up fibers – I’d like to do the next experiment with an alumina crucible. I’ve got the next experiment setup ready, would just need to free up a couple of days to actually execute. Probably this year still…

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