Sometimes it's reported brownish in colour. I would like understand the reason for the colour formation.
The colour of graphene-derived species depends on the flake size and on the functionalization degree. Brown means that you would have more of a mixture of species, if it's yellow, the spread of size and functionalization degree might be smaller since the absorption is more defined, so depending on what you want to reach, that might actually be a good thing.
Hii , Jayanta Parui ,
Hope you doing well.
It was really interesting question.
I'm strongly agree with Jürgen Weippert .
But, also as per my knowledge the aqueous solution of graphene oxide is typically yellowish to brown in color. However, if the graphene oxide is slightly reduced, its color will become black, as will its solubility.Therefore,
1. Take a Raman spectra of your black product, and notice if the ratio of Id/Ig is significantly improved, which indicates the level of your oxidation. color depends on oxidation also.
2. take a TEM and notice if the graphene layers has been sufficiently exfoliated. If your material is not exfoliated well then it also affects color of material.
3. Dry your material at 98` C temperature. So, that strong oxidant reduce from your material.
4.Yellowish to brown color when dispersed in water.
5. When the graphene oxide is washed with HCl and Deioniozed water its colour change to light brown or dark brown due to removal of impurities.
You may want to check out the following article :
1.Improved synthesis of graphene oxide.
Article Improved synthesis of graphene oxide. ACS Nano 4:4806-4814
2. A Simple Approach to Stepwise Synthesis of Graphene Oxide Nanomaterial
Article A Simple Approach to Stepwise Synthesis of Graphene Oxide Nanomaterial
I hope this articles help and clear your doubts. Good luck with your research!
Best wishes & Regards,
Vishwajit Chavda
Hi, Jayanta Parui
The colour of graphene oxide depends on the oxidation degree of graphite and the particle size of graphite.
Thank you all for sharing interesting information and observations related to graphene oxides. I was trying to understand the origin of the colour. Precisely, which is the electronic transition responsible for the color? Please share if you know. Thank you
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