Hello all,
Could anyone suggest me how to get a very uniform graphene oxide film? I used dip coating, spray coating and spin coating of GO on glass slide. But none of these methods worked. When I observed the surface morphology of graphene oxide using profilometer, I could see a very uneven surface.
Thanks in advance
Hi Shawana,
You can use a spin coating with control on the parameters which mainly limit on the film growth such as a rotation speed and time. The film thickness as well as uniformity depends on it. Make sure after every complete rotation keep a hot plate on to heat the film by some temperature(85~100 0 c). And basically there is no such rule or fixed method to get an uniform film. Thus, it's important to know the use of organic solvent instead of the DI water.
Regards,
Graphene oxide is hydrophilic in nature due to the existence of oxygen- containing functional groups hydroxyl, epoxide, carbonyl and carboxyl , while glass substrate is hydrophobic . You must to make the glass substrate as highly hydrophilic surface by adding OH groups via treatment with mixture of hydrogen peroxide and sulfuric acid( Piranha solution).
https://en.wikipedia.org/wiki/Piranha_solution
Depends on how thick you desire for the film (isolated flakes or a continuos surface). For a thicker film you could try to slowly dry an aqueous solution with the substrate on the bottom part of an becker, i.e. at 60-70 oC.
It is important to have a clean and hidrophylic surface. It remains some water withing the film, mainly for thicker films, but it is normal since the functional groups on GO cage a little water molecules between the GO layers anyway.
You could try that.
Best Regards.
100% Uniformity layer in graphene is Almost impossible but the highest level of it is possible...all types of coating process your already did it can give and optimize the layer by repetitive trying and change the parameters of coating process ...some others used CVD and it gives good results of uniform graphene layer...by the way ..how much thickness your working on in nano or micro?
Thanks everyone for your valuable suggestion. The spray coating finally worked but I had to try many times to optimize the film thickness
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