I am preparing graphene oxide by improved hummer's method.I would like to fully understand the mechanism and role of each reagent added to the protocol, any suggestions of reference articles that might be helpful?
Thank you Mr. Dmitri for the very helpful article..
I also would like to know, why do we heat mixture up to 50 C,after adding all reagents, and then pour it on ice before centrifugation with water and ethanol? does the heating help in oxidation reaction??
Regards
Hi,
A mechanism is difficult to describe because there are many different protocles all called "modified" oder "improved" hummers method.
I assume you use 98% H2SO4/MnO4-/(NO3-), Water, 3% H2O2.
Sulfuric acid intercalates the grapheen sheets if oxidant is present. While you heat the graphite and the oxidant up, the graphite becomes higher oxidized by manganheptoxide (additionally you introduce more defects inside he lattice structure due to carbon loss). The oxidized graphite intercalation compound the reacs with water to form GraphitOxide with covalently bound oxygen species. Then It is poured on ice water because there may be uncontrollable temperature elevation of the reaction between water and sulfuric acid. H2O2 is needed to transform unsolulible mangan species to Mn2+. Ethanol may increase the yield because less oxidized sheets in the core of the crystals may not be exfoliated by pure water molecules.
Hope it helped you a little bit.
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