Following the Hummers' method "flow sheet" (H2SO4, KMnO4 and NaNO3) and collecting the solid at the end of the synthesis for the XRD characterization I do not see any peak in the range 5-20 2-theta even if the classic graphite peak at 26 2.theta disappears. Moreover the solid obtained is not hydrophilic as I wished. The XPS suggests a low modification of the graphite surface.graphite
Do you have some suggestion?
Thanks
Normally the Hummers method is efficient to obtain graphene oxide from graphite. Your results suggest that your final solid is not oxidized enough (no modification on XPS, hydrophobic material). Maybe try with smaller quantities or longer reaction times? 1-2h at 90°C are necessary for 1 g of graphite.
I agree with Lea. Reaction times are critical for the effective oxidation of graphite. Can you describe the exact procedure you follow?
1 g of graphite was put in a becher with 10 g of KNO3 (with the possibility to use the NaNO3). The becher is put in an ice bath with salt and a thermometer was used to keep the control of the temperature during the reaction. A sulfuric acid 98% was gradually added (230 ml) and once the temperature was stabilized the ice bath was get off.
The temperature was maintained to 35 °C for at least 20 or 30 minutes and an equal amount of water was gradually added. The temperature was maintained to 98°C during this procedure, and once that the total water was reacted the temperature stopped to increase.
The solution was left under stirring. Once the environmental temperature was reached the solution was centrifuged to separate the acid solution and solid. After that the solid part was left in de-mineralized water for one night in order to permit to the graphite oxide to deposit at the bottom of the becher.
The day after the water was get off and the support was heated to 50°C. Reached this temperature a solution of 3 %of H2O2 was added by slowly.
The solution obtained was left under stirring for 15 minutes with the following deposition of the solid.
At the end the solid support was dried in the oven for one night (range from 110° to 150°C).
I used this paper for the synthesis of GO (Chem. Mater. 2010, 22, 1392–1401) and got perfect results. You can check my papers for FTIR, XRD and other analysis. I think your graphite has not been oxidized.
i'd say its better to use the improved graphene oxide synthesis method rather than hummers or modified hummers .
Read the Paper "improved synthesis of graphene oxide", from ACS Nano, by marcano,kosynkin, berlin, et.al.
No use of NaNO3 and better results of oxidation. We didnt use the membranes and fibers written in the paper but still got the best results in UV, SEM, TEM, etc
did u add kMnO4 under ice bath, did u heavily washed the product with water and low con acid solu
hummers method is a good one to get GO
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