Department of Materials Science and Engineering, New Jersey institute of Technology, Newark, New Jersey, 07102, USA.
Department of Chemistry and Environmental Sciences, New Jersey institute of Technology, Newark, New Jersey, 07102, USA.
Sci Rep. 2018 Jul 4;8(1):10083. doi: 10.1038/s41598-018-28353-6.
Graphene Oxides (GO) typically contains different oxygen containing groups such as hydroxyl, carboxyl and epoxy, and reduced GO (r-GO) represents a family of material with diverse chemical properties. In an effort to understand how properties of r-GO change as GO is reduced, a stepwise reduction of the same GO to r-GO containing different levels of oxygen was carried out, and their corresponding chemical and colloidal properties are reported. Starting with GO containing 49 percent oxygen, r-GOs containing 31, 19 and 9 percent oxygen were synthesized. 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 MgCl as the oxygen in the original GO was reduced to 9%.
氧化石墨烯（GO）通常含有不同的含氧基团，如羟基、羧基和环氧基，而还原氧化石墨烯（r-GO）则代表了一类具有不同化学性质的材料。为了了解 GO 被还原时 r-GO 的性质如何变化，我们对同一种 GO 进行了逐步还原，得到了具有不同含氧水平的 r-GO，并报告了它们相应的化学和胶体性质。从含氧量为 49%的 GO 开始，合成了含氧量分别为 31%、19%和 9%的 r-GO。从溶解度方面来看，r-GO 的水溶液行为逐渐从 7.4μg/ml 的 GO 降低至几乎为零的 9%含氧量 r-GO，而超声分散度则从 8μg/ml 降低至相同样品的 2.5μg/ml。疏水性指数（以辛醇-水分配系数衡量）从-3.89 降至 5.2%，而含氧从 49%降至 9%。胶体行为也受到还原的显著影响，在 0.5mmol/l NaCl 存在下，临界聚沉浓度（CCC）从 28 降至 15，在 0.5mmol/l MgCl 存在下，从 6 降至 2，而原始 GO 中的氧被还原至 9%。
