I synthesized graphene using the tour method and got 4g of GO sludge. Reduced it using in situ hydrogen reduction using al and hcl after washing it with hcl, ethanol and neutral ph. When I dry the whole thing out on a paper(pour cast), the resistance in ohms is >400/cm or sometimes kohms. Why is it high? People report like 9 ohms/cm
When I was reducing it, I poured the whole sludge into like like 500 ml water and tried reducing it (almost 8mg/ml). Is my reduction not happening properly because the solution is too concentrated? When I swirl the contents, I can see big particles flying around in the solution , which quickly settles in a couple of hours. People also report RGO solutions are stable for weeks. Mine seems to settle in a day. Sort of stuck here... One of the ideal I have right now is make 0.5 mg/ml solutions > reduce them using ascorbic acid and combine them. What are your thoughts?
Your GO particle size is too large.. That's resulting quick precipitation and high resistance. And also for large particle size, deep reduction is more difficult. All these are happening due to too high concentration. Reduce your concentration a lot... You can also reduced reducing reaction by reducing the solution temperature, this will enhance deep reduction process. Use Sonication to break-down your particles and use centrifugation to remove large particles from your solution then try make paper and check resistivity. The resistance should be much lower, using above.. You can check out this paper for more details.
Article Solution-Processed Graphite Membrane from Reassembled Graphene Oxide
Great Chandan..I will give this a shot. Now I guess I know why graphene is so expensive!
It is depend on reduction degree and method. If there is any residual graphene oxide, graphene resistance will be high.
Thanks Mohamed.. I suppose that and too high concentrations of GO during reduction is the issue. I think so because I just tried the sodium sulfate intercalation method and go some great exfoliation using 7.2v and 0.4amps. Washed the exfoliate throughly > sonicated for an hour in water and drop casted it on some paper and let it dry. Initially my samples read 1.6k ohms. After heating the paper for a couple of minutes at 120 degrees, the resistance dropped to 300 ohms (2 mins heating).
The coating was brilliant and smooth.. the color was silvery black (not as silvery as expanded graphite) as opposed to my black graphene suspension.. Do you guys thin this is agglomeration into graphite?
Also, is there is way for me to figure out how much graphene I have from the exfoliate I have after sonication?
so the issue was the extent of reduction.. DIY graphene battery works now
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