It is very difficult to get a suspension of graphene in water.For dispersion we do sonicate graphene in water for several hours.You can try

yes. I think that 2 hours is enough for sonication.

do you have XRD and Raman test of your sample?

tnx for your answers ,

In your opinion , is it necessary to use any kind of surfactant during sonication, such as SDS or CTAB ?

You need to disperse graphene in water. Why surfactant?

Some papers report that surfactant has positive effect on dispersion of CNT in water also has preventive effect on agglomeration ,So I guess it perhaps has same effect on graphene dispersion too !

I haven't used yet. we can test it. could you please send me your article?

[email protected]

As far as I know, CVD does not provide graphene powder. Can you please let me know where did you get the CVD graphene powder?

There are a lot of cheaper options to make graphene powder, which is redispersible in water, such as reduced graphene oxide, sonicating graphite/surfactant and ball milling of graphite.

tnx for your kind recommendation. Actually I bought these graphene in shape of large flakes ,But I need to a suspension of fine graphene sheets in water, So milled them to reach graphene powder, But now i guess their structure may be deformed by

milling !!! I'm really confused, Perhaps I wasted a lot of money :-(

Actually what is the best , simplest and Cheapest option ?

I have mostly worked with graphene oxide.

With graphene oxide, in water, you can make your material (composite, ...) then expose them to a reducing agent. Also there are ways to have reduced graphene oxide in water. (Nature nanotechnology 3 (2), 101-105)

If you want to use graphene oxide, I would suggest to synthesis that by yourself its very easy.

If you seek for other options, just add graphite powder (1 mg/ml) to a surfactant solution (such as SDS 5mg/ml) or organic solvents (NMP, DMF).

Bath sonicate the mixture for at least a day. Then let them rest for an overnight followed by 1h centrifugation for at least 5000g. The top of the dispersion will contain graphene (1-5%) and few layers graphene.

@Rouhollah Jalili

Thanks for your kind recommendation. That paper was really helpful. And I'm going to try with GO this week ,Thank you again.

I used sonictor to disperse GO in water but I can not separate GO from water by centrifuge. can you suggest better way to obtain GO?

I guess ,you can directly filtered the suspension or dried it in a vacuum

oven to obtain bulk powders.

Dear Molood

Did you obtain suspension of Graphene in water?

Did you use any surfactant?

Dear Molood ,

Surfactants are the best way to obtain a better graphene -Water dispersion. try with SDS , if you are working with concentration below 1mg/ml . then you can use low SDS concentration (the best dispersion is obtained at a concentration of 2.8 mM which is the Sac concentration ( the surface aggregation concentration ). if you are working with very higher graphene concentration you should use SDS concentration above the CMC (Critical micelle concentration).

This publication may help you :

High-yield graphene exfoliation using sodium dodecyl sulfate accompanied by alcohols as surface-tension-reducing agents in aqueous solution.

To make a suspension graphene added in to water(e.g 3mg/ml) and sonicate it 5-10 minutes.

hi, which would be better - ultrasonication or bath sonication to disperse? thanks

Bath type sonicators offer mild mixing due to their indirect transfer of energy. Probe type sonicators offer aggressive shearing which may alter the physical properties of FLGs.

I suggest you try bath type first, see if that works for you. If not, probe type it is.

Thank you. I have tried ultrasonicator for GO dispersion at 30% amplitude now im afraid if Ive damaged it before reduction; after which i did bath sonication. Should i expect my RGO particles to be completely homogenized because i dont know if its sufficient already when i still see separate particles at 25mins.