Graphene Oxide (GO) contains different oxygen containing groups such as hydroxyl, carboxyl and epoxy. Oxygen containing groups can be removed chemically to reach reduced GO (rGO) which has different chemical and physical properties than GO. In following research chemical and colloidal behavior of rGO corresponding to different oxygen containing groups was studied. Starting with GO containing 49 percent oxygen, rGOs containing 31, 19 and 9 percent oxygen were reduced stepwisely. The aqueous behavior in terms of solubility gradually decreased from 7.4 μg/ml for GO to nearly zero for r-GO with 9% oxygen, while dispersibility under sonication decreased from 8 to 2.5 μg/ml for the same samples. Hydrophobicity index as measured as the octanol water partition coefficient decreased from −3.89 to 5.2% as oxygen content dropped from 49 to 9%. Colloidal behavior was also dramatically affected by reduction, and critical coagulation concentration (CCC) dropped from 28 to 15 in presence of 0.5 mmole/l NaCl and from 6 to 2 in presence of 0.5 mmole/l MgCl2 as the oxygen in the original GO was reduced to 9%.

Colloidal and chemical properties of graphene oxide and step wisely reduced graphene oxide

2019 Spring National Meeting

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