GO was prepared using the modified hummers method, XRD analysis showed a broad peak at around 24°(pic attached), I am not sure what this indicates.
Lit. survey shows that both graphite as well as rGO show a peak around 24°, the peak of graphite is extremely sharp, whereas the peak of rGO is very small, however my sample shows a rather big broad peak so I am rather confused as to what this peak indicates.
Note that I extensively washed my sample using the centrifuge in order to remove all unreacted graphite so chances of graphite remaining are low. Also, I did not perform any reduction procedure so what could have caused the GO to reduce?
Thank you.
Graphene is very light to XR, the Xray beam is looking the plate. Try to change to another plate or record the XRD of the plate and subtract it from the diffractogram
Dr. Briones,
Actually yes, the sample plate is of glass! But I dont understand how it could interfere with the scan...
Graphene is very light to XR, the Xray beam is looking the plate. Try to change to another plate or record the XRD of the plate and subtract it from the diffractogram
Right. The XRD pattern around 24° is very broad. It can come from an amorphous sample.
The attached pic shows an XRD similar to mine and the broad peak is due to reduction process performed, as I mentioned earlier I did not perform any reduction procedure so now my question what are some possible factors that could have cause reduction in my sample?
I am aware that heating is one of them but my sample dried at 35C so I dont think heating is the reason in my case.....
I am curious on how the authors of the attached diffractogram attribute the wide peak to reduced graphene oxide. Do they performed an XRD comparison of GO with different O/C ratios? Because the wide peak still seems glass to me, just smaller thatn your. But if it really comes from a reduced material you could check your lab if there was an exposure of your GO sample to lets say, an active metal such as Al, Zn or Fe, or to a reducing environment such as H2, N2, Ar or to a reducing salt or to reducing sugars. Otherwise, an spontaneous reduction seems not very likely, but if that is the case, you could check for example the molecular structure, i.e. which moieties are present in the as-prepared, non-reduced sample compared to those in the reduced one and try to state a mechanism of reduction that works close to RT.
The broad peak is significant indicator of amorphous materials. The one shown above is from some other source.
You may now take the XRD with thick layer of GO (1-2 mm or more). If you see any reduction in the intensity of the broad peak, assure that it is from the glass plate or the substrate material.
Dr. Briones, here is a link to the article if you wanna read it http://www.hindawi.com/journals/jchem/2013/150536/
Thank you Aisha. Still not convinced on the XRD, or better, more convinced that it is the glass plate you are using as holder. Note that the so-called amorphous graphene halo is the same in RGO and GO except for the intensity and this could be due to the different background the measurements have. The most convincing results they show are the Raman spectra where the D band reduces and 2D band appears upon reduction and maybe the FTIR, Regards
Yes, to confirm GO, Raman spectroscopy is definitely the most preferred one.
Thanks for the insight everyone, unfortunately I do not have access to Raman. I have another question...
Does partially oxidized graphite have similar structure as rGO? In the sense that partial oxidation will only result in a few oxygen groups being inserted between the layers, similary in rGO there are always some oxygen groups left behind even after reduction so basically both have a few oxygen groups between the layers resulting in similar interplanar distance.
Not sure if that makes a lot of sense....
You will have oxygen groups inserted between the layers that are the cause of the interplanar distances (in fact the interplanar distance depends on which groups as some will increase and other decrease it) but also in the edges as carboxyls, carbonyls and phenols. RGO still keeps oxygen groups and it depends on which are reduced in fact to influence the interplanar distance. But the conductivity, i.e the restoration of the sp3 character in the sheet plane, it is fact increased.
Dear Aisha, please find an Origin dataset to answer your query, hope it is useful
This spectrum seems to suggest that the exfoliation may be incomplete. Probably you have a high graphitic retention, i.e. unoxidized regions. Try to increase the reaction time and the stirring speed or, eventually, change the synthetic route.
I have also prepared graphene oxide and reduced graphene oxide . I got a sharp peak at around 10 and also i got a peak at 23 but that is not so sharp and very less in height as compared to the peak at 10. The peak at 23 is due to incomplete oxidation of graphite , graphite can't be oxidized 100% . If you have oxidized it ti a good level then you can clearly distinct between those peaks.
@Chandra: "oxidation level" of 50% (i.e. sp2 retention close to 50%) is high enough to increase interplanar distance. Potassium permanganate breaks basal planes of graphite, H2SO4 is able to intercalate between lamellae. Finally the oxygen moieties (even at 30-40% of oxygen) are able to increase the distance between planes. Water molecules are integrated in the structure, thus contributing to an increased interlamellar distance. Whenever you see peaks at 23-26° your reaction has somehow failed. I prepared batches of graphene oxide under 10-15 different conditions and only once I found a peak at 24-26°. The exfoliation/oxidation/chemical, physical, geometric features of GO crucially depend on the pathway you follow (i.e. synthesis+work up).
- Badges
- Science method
- Similar topics
- Methodology
- Crystallography
- X-ray Diffraction
- XRD Analysis