| Pages:
1
2 |
WGTR
National Hazard
Posts: 971
Registered: 29-9-2013
Location: Online
Member Is Offline
Mood: Outline
|
|
Quote: Originally posted by WGTR  | I managed to oxidize some flake graphite using an adaption of the electrochemical method.
I thought I had graphite foil, but it turned out to be some strange paper made from carbon squiggles. It exfoliated in a really weird and useless
way. |
Well, I'm going to have to eat my socks. After several more hours, my precious exfoliated flake graphite precursor settled out of the DMF solution.
It is not as exfoliated and/or oxidized as I had thought. I should have known better. It was an optically black solution. Partly oxidized
graphene will have at least a bit of brown in it when it's in solution.
On the other hand, the "useless" squiggles from the graphite foil turned out to be more useful than I thought. After bumping up the anode current
density a bit, the solution started turning a little brown. The ribbons of oxidized graphite were mostly floating. These were scooped out and
washed with DI water, and then sonicated in DMF. There is still a lot of unexfoliated graphite/graphite oxide floating around in the solution. It
will take a few days for it to settle out, probably. If it doesn't, then I'll go out back and use the centrifuge. Even now, this solution does look
brown when in a strong light.
Anyway, I hope my haphazard experiments aren't too frustrating to people. I'm really short on time right now. When I can, I'll throw some stuff in
the SEM and try to characterize it.
|
|
|
forgottenpassword
Hazard to Others
Posts: 374
Registered: 12-12-2013
Member Is Offline
Mood: No Mood
|
|
Graphite and a kitchen blender is today's scientific breakthrough method, knocking the Scotch tape and pencil method off the top spot! http://www.bbc.co.uk/news/science-environment-27113732
"An Irish-UK team poured graphite powder (used in pencil leads) into a blender, then added water and dishwashing liquid, mixing at high speed.
The results are reported in the journal Nature Materials."
http://dx.doi.org/10.1038/nmat3944
[Edited on 22-4-2014 by forgottenpassword]
|
|
|
elementcollector1
International Hazard
Posts: 2684
Registered: 28-12-2011
Location: The Known Universe
Member Is Offline
Mood: Molten
|
|
Apparently, even the brand and amount of dishwasher detergent factors in? This is going to be another Potassium, where we all report tries with
different brands of solvent, isn't it. 
Might just try this - I used to collect broken pencil leads for obtaining graphite, but eventually threw it away as I had no real use for it.
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
|
|
|
IrC
International Hazard
Posts: 2710
Registered: 7-3-2005
Location: Eureka
Member Is Offline
Mood: Discovering
|
|
I'm going with the OP's link. Ordered Ammonium Sulphate 4 lb and have graphite out the wazoo. Even have two new crucibles made of pure graphite that
weigh 90 lbs each. Monsters that take up large area in storage. Don't ask no idea what they were made for but it was big whatever it was. Plus many
reasonable size electrodes of graphite, and many Ti and W electrodes. But only a small amount of Pt wire, the reason for my earlier question still
unanswered. Just going to try it with a Ti rod 1/2" x 12", and a similar size graphite rod and see what happens.
What I was wondering about and hope would be answered by someone good at chemistry is if I run say 10 amps through an Ammonium Sulphate solution with
one electrode of graphite and the other Ti or W, do I need to worry about any undesired side reactions and products/gasses/U name it coming out of the
cell?
| Quote: Originally posted by elementcollector1 | | Apparently, even the brand and amount of dishwasher detergent factors in? This is going to be another Potassium, where we all report tries with
different brands of solvent, isn't it. |
On page one of this thread I posted a link to the NewScientist version of this article which gives specific info:
"The team put graphite powder and a solvent fluid in a laboratory mixer and set it spinning. Analysis with an electron microscope confirmed that they
had produced graphene at a rate of about 5 grams per hour. To find out how well the process could scale, they tried out different types of motors and
solvents. They discovered that a kitchen blender and Fairy Liquid, a UK brand of dishwashing liquid, would also do the job.
"If you are using a blender, why use a fancy expensive surfactant? Why not use the simplest surfactant there is, and I guess that is Fairy Liquid,"
says Coleman.""
I have to wonder, my bean grinder has sharper blades rotating at much higher velocity. Only question is how good is the shaft seal?
"Science is the belief in the ignorance of the experts" Richard Feynman
|
|
|
Baffled
Harmless
Posts: 16
Registered: 24-1-2014
Location: Milky way
Member Is Offline
Mood: No Mood
|
|
This article cought me by surprise:
http://www.sciencedirect.com/science/article/pii/S0142961212...
This (supposedly) is the full article:
http://extremelongevity.net/wp-content/uploads/C60-Fullerene...
If only we had more helium, not all at once though, that wouldn't be cool
|
|
|
Mildronate
Hazard to Others
Posts: 428
Registered: 12-9-2009
Member Is Offline
Mood: Ruido sintetico
|
|
Oganic graphene analog http://pubs.acs.org/doi/abs/10.1021/ja502765n
|
|
|
Dan Vizine
National Hazard
Posts: 628
Registered: 4-4-2014
Location: Tonawanda, New York
Member Is Offline
Mood: High Resistance
|
|
A statement to the effect that graphene is the "future" of energy storage is overly broad. That graphene will be enormously important is not debated,
it's the how that remains to be seen.
The real stars of energy storage into the forseable future are, naturally, the batteries that utility companies plan to use for off-peak power supply
in order to make solar and wind energy practical. Nobody is talking about graphene here, where the emphasis is on inexpensive starting materials and a
high number of cycles/battery. Here they talk about sea water, iron, prussian blue, zinc and manganese dioxide.
So, what electronics is graphene going to revolutionize first? Let's look at the properties.
One of the most noteworthy (although, personally, I'm more interested in the mechanical uses like gas separation, but that's a chemist for you)
features of these 2D sheets is that allowable energy levels are continuous (zero bandgap, which is the energy difference between the conduction and
valence bands ) and that conduction electrons behave oddly as a result. Instead of exhibiting normal fermion behavior where E is proportional to the
momentum squared, in graphene the electrons (conduction), behave more like light does and E is directly proportional to momentum. The electrons
literally mimic massless photons in spatial regimes defined as "Dirac cones". In these regions, conduction electrons all travel at the same high speed
and so metal-like conductance is seen in something that is often more accurately called a "zero-bandgap" semiconductor.
But, the fact that no significant bandgap exists means that you can't make a transistor from it. You must open a bandgap. But, the things that open
bandgaps (cutting, strain, doping) reduce electron mobility. This trade-off is the devil in the details. Actually, let me qualify that a little
bit...there has been a recent proposal to open "tunable" gaps in graphene through a combination of strain and an electrostatic field that supposedly
doesn't reduce electron mobility. I don't think this is proven in the lab yet and, honestly, I don't fully grasp how it works.
The important point is that, while graphene is great for supercapacitors, should improve photovoltaics and will probably be a means for
increasing the energy density of Li batteries (because it can act as a very high capacity Li ion host although very significant cycling problems
currently exist), so far nobody can say if graphene, a graphyne (with alkynyl bridges and less symmetrical) or even the significantly more complicated
silicon analogs, silicenes, will be the material of choice in the future. For example, silicenes offer better interfacing with our existing
silicon-based devices and they have their own unique Dirac cones. One hopes that we will waste less time between theoretical predictions and some kind
of real-world actualization than we did with graphene, but that seems assured. We can make the latter types already, unfortunately the amounts
produced are quite small so far.
Silicenes, btw, don't exhibit the simple, but elusive, silicon sp2 hybridization scheme. Thus, they are 3D sheets, more than one atom in thickness.
[Edited on 28-4-2014 by Dan Vizine]
|
|
|
Dan Vizine
National Hazard
Posts: 628
Registered: 4-4-2014
Location: Tonawanda, New York
Member Is Offline
Mood: High Resistance
|
|
Sometimes, things move fast when a huge number of scientist focus their energies. Graphene just took another big step forward, as announced about a
week ago:
http://nanotechweb.org/cws/article/tech/57080
Growing graphene on hexagonal boron nitride allows the lattice mismatch to open tunable bandgaps without the performance penalties (apparently) of
existing methods.
|
|
|
Baffled
Harmless
Posts: 16
Registered: 24-1-2014
Location: Milky way
Member Is Offline
Mood: No Mood
|
|
http://www.youtube.com/watch?v=t5qLfHLyQKo
Did he say "eat"?
|
|
|
forgottenpassword
Hazard to Others
Posts: 374
Registered: 12-12-2013
Member Is Offline
Mood: No Mood
|
|
I have 100g of graphene powder. What can I practically do with it?
|
|
|
WGTR
National Hazard
Posts: 971
Registered: 29-9-2013
Location: Online
Member Is Offline
Mood: Outline
|
|
That depends mostly on how it was made, assuming that what you have is in fact graphene powder. The exfoliation of graphite into graphene is easily
reversable. How was it made/obtained?
|
|
|
forgottenpassword
Hazard to Others
Posts: 374
Registered: 12-12-2013
Member Is Offline
Mood: No Mood
|
|
It was made by the incomplete combustion of ethanol. There is no doubt as to its identity.
|
|
|
forgottenpassword
Hazard to Others
Posts: 374
Registered: 12-12-2013
Member Is Offline
Mood: No Mood
|
|
No suggestions at all?
|
|
|
WGTR
National Hazard
Posts: 971
Registered: 29-9-2013
Location: Online
Member Is Offline
Mood: Outline
|
|
The reason that I asked how it was made, is because it's usefulness for different applications depends on the different functional groups that are
attached to it. If it's pristine curved nano sheets of graphene, then you could grind the powder together with a plastic binder and conductive
additive, and form thin super capacitor electrodes. This type of material can also be used to increase the strength, thermal conductivity, or
electrical conductivity of epoxy, etc.
I'm on an iPhone right now, so I'm away from my references.
[Edited on 6-23-2014 by WGTR]
|
|
|
Baffled
Harmless
Posts: 16
Registered: 24-1-2014
Location: Milky way
Member Is Offline
Mood: No Mood
|
|
Now that I think of it, I once (about 10 years ago) demolished an old vacuumcleaner and tried using the carbon brushes for the production of chlorates
with some lo-salt and an old universal ac/dc adapter. I soon got tired of the rapidly heating adapter and tossed in some hand soap containing mostly
sodium laureth sulfate to see if I could get the bubbles to mix enough on the surface to produce a bang.
I didn't succeed in making enough bubbles to make the two gasses to mix, but I did notice an "oily" rainbow on the surface (like this) after a couple of hours. I tossed it in the toilet thinking it was just some oil residue that made it's way into the brush from the electric
motor, but I still have the flowerpot, adapter and the carbon brushes.
I'm still alive.
Edit: checked the flowerpot, it appears I have some graphene oxide (a few yellow/brownish areas a few mm2 across) suspended on ceramic
glazed substrate (the flowerpot). I think I should measure its resistance to be sure.
[Edited on 25-7-2014 by Baffled]
|
|
|
| Pages:
1
2 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
