I have a bottle of monolayer graphene oxide (GO) water solution. The concentration is about 2 mg/ml. But I don't know how to get a uniform monolayer or several layers of GO on a piece of 4 cm*4cm carbon paper. The process needs to be done under 150 ℃. Thanks a lot.
@Yichang Yan
You can use a slot-die coating technique or bar coating. Alternatively a spray coating is also a very effective way for a large area and homogenous film coverage on a substrate.
Hope it helps.
If you can follow the current yiu will get a maximum current which refer to a mono layer then the reduce in current amount indicatescthe second layer or multi layers performed
Xuhua Wang
Thanks a lot. I will try the spray coating when my university reopens.
Do you think the graphene oxide pieces will connect with each other to form a whole film when it is dry? I mean in your opinion, do you think the graphene oxide film will be able to block water or ethanol, or this formed layer could reduce the permeability of liquid. Or is there any way to achieve it?
Thanks a lot and looking forward to your reply.
Amer Al-Taee
Thanks for your answer. Could you please explain it more specifically for me. Sorry didn't fully understand the idea.
Paolo Passaretti
Yes, it would be best to be deposited on carbon paper. Or it is also okay to be deposited on a piece of PTFE. But after that, I still need to transfer the film onto carbon paper by a de-cal method. Do you have any idea or suggestions? Thanks a lot.
Dear Yichang Yan,
To answer your question,
1. Do you think the graphene oxide pieces will connect with each other to form a whole film when it is dry?
YES, you need to spray layer by layer for a coverage of whole substrate. What you can do is to put your substrate on a hot plate, set-up temperature is around 100 degree C to dry your film at the same time to spray coating. You can make a disirable layer thickness by controlling the spraying coating time.
2. do you think the graphene oxide film will be able to block water or ethanol, or this formed layer could reduce the permeability of liquid. Or is there any way to achieve it?
To answer your second question, please see the link below regarding the properties of graphene oxide films for blocking liquids.
https://www.nature.com/articles/s41598-019-38485-y
Hope it helps.
Best wishes
Xuhua Wang
Xuhua Wang
Really appreciate for your help. I will read through it and carry on with your suggested method.
Hi, To synthesize Hummer's-modified graphene oxide, mix 200 g of sulfuric acid for each 1 gram of expanded graphite and place it on the pan to soak the whole graphite with acid. Slowly add 9 g potassium permanganate to the mixture, which changed color to green. After 24 hours of mixing, add 200 mL of very slowly ionized water to the resulting mixture, which will change the color to a strong brown.
After half an hour of mixing, add mL 35 oxygenated water to the mixture to stop the oxidation process and residual permanganate and stir for another half hour. The color of the mixture in this section changes to light brown. The resulting mixture is very corrosive. The next step is to wash the mixture using a 9: 1 solution of hydrochloric acid: 4000 rpm concentrated water.
Continue rinsing more with water until the pH of the mixture reaches neutral. After complete centrifugation, dilute the graphene oxide plates in ionized dehydrated water and then, using a phoneme vibrator for two minutes, to obtain graphene oxide supplements in the water.
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