GO is brown in colour and water soluble and rGO is black in colour but which analytical tools help to distinguish between both.
Dear Paresh Gaikar ,
Really a good and interesting question you asked.
First of all, Graphene won't dissolve in water or organic solvents. It only disperse in solvents. Pure or pristine graphene display poor dispersion due to the strong van der waals force of attraction. Functionalization of graphene (GO or rGO) is the only option to disperse in water or some solvents.
So, Back to your question , that for my opinion best analytical tool to distinguish between GO and rGO was XRD, Raman, and IR.
- RAMAN : From D vibration band and G vibration band you can distinguish GO and rGO. ID/IG ratio for GO was determined to be 0.86. After reduction, the ID/IG for rGO was increased due to the restoration of sp2 carbon and decreased in the average sizes of sp2 domains upon reduction. Higher intensity in D band also suggested that more isolated graphene domain were presented in rGO as compared to GO and also due to removal of oxygen moieties from GO after reduction.
- XRD : For graphite, one sharp peak can be observed at 2θ = 26.62°. For GO, the 2θ peak can be seen to be shifted to 9.03°, which indicated that the graphite was fully oxidized into GO. After oxygen-containing functional groups were eliminated significantly during the chemical reduction, a broader peak can be seen for rGO at 2θ = 24.10°. This indicates that the π-conjugated structure of graphene has been restored considerably at the produced rGO.
- IR : for GO, the intense and broad peak that appeared at wavelength of 3420 cm-1 confirmed the presence of O-H bond (hydroxyl group).For rGO, the peak at 3420 cm-1 became less broad as compared with GO proving that the hydroxyl group was removed significantly.
You may want to check out the following article :
1. Comparison on graphite, graphene oxide and reduced graphene oxide: Synthesis and characterization
Conference Paper Comparison on graphite, graphene oxide and reduced graphene ...
2. Comparison of the characteristic properties of reduced graphene oxides synthesized from natural graphites with different graphitization degrees
Article Comparison of the characteristic properties of reduced graph...
I hope this articles help and clear your doubts. Good luck with your research!
Best wishes & Regards,
Vishwajit Chavda
It was a very good explanation by Vishwajit Chavda. Further, I would like to add on a very essential characterization technique to differentiate between GO and rGO i.e. X-ray Photoelectron spectroscopy (XPS). XPS is used to quantify the elemental composition. Usually, the basic difference between GO and rGO is the amount of Oxygen present in the form of oxygen containing functional groups. GO contains large amount of oxygen compared with rGO. XPS can be used to quantify the amount of Carbon and Oxygen present. The ratio of Carbon to Oxygen (C/O) gradually increases after the reduction from GO to rGO which can be calculated by XPS.
For detailed explanation you can go through the article below.
Thank you Rita Joshi , for adding a one more analytical technique to this discussion.
Good explanation about the comparison between the GO and rGO by Vishwajit Chavda and Rita Joshi . I have also compared rGO synthesized by using different reducing agents like hydrazine hydrate, sodium borohydride and ascorbic acid. The black colour and insolubility in water are the initial indications for the formation of rGO from GO. The analytical techniques used for characterization are XRD, FESEM, EDS, UV and Raman spectroscopy. The C/O ratios are also compared for GO and rGOs using EDS. The absorption peak for GO is around 232 nm and it is shifted to 263 nm when reduced into rGO. The lowering of the energy bandgap (calculated using Tauc Plot) also confirmed the reduction of GO into rGO.
Detailed explanations are given in the published research articles.
you can see them Paresh Gaikar
For quick characterisation, you can use UV-Vis, Raman spectra and FTIR.
Several characterization techniques can be used to distinguish between graphene oxide (GO) and reduced graphene oxide (rGO). Here are some of them:
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XRD technique can be instrumental to differentiate the GO an rGO , where 001 peak appeared for GO at 2thta =7-11o and 002 peak for rGO 2theta =26-27o
you can conduct ESR , PL NMR analysis also and for more details go through the following paper
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