Hydration of Graphene Oxide

Graphene oxide has been known and used since 19th century. It is a non-stoichiometric compound which means the ratio of the atoms in the compound are not of definite proportions. The lowest ratio of Carbon, Oxygen and Hydrogen is 6:2.33:1.2 and the highest is 6:3.7:2.83 by Brodie's and Standenmeier's method, repectively. (Those methods are named after the scientist who published the paper). 

Graphene oxide is hydrophillic, which means they like water and they would attract water molecules to be suspended in water. Its hydrophillicity was discovered by adding water to graphene oxide and measuring the distance between the layers. 

As the graph shows, it turned out that as the humidity increased, the distance of the layers also increased, which meant that they made bonds with water. Now they replaced the hydrogen atom with the deuterium atom to see if they same thing happens, and the distance between the layers matched, which could be firmly concluded that graphene oxdie is hydrophillic and make bonds with water molecules. In order for them to make chemical bonds with water, the water needs to be of low electrolyte concentration and slightly basic. If the water has high electrolyte concentration and slightly acidic, the graphite oxide would not make bonds with water. However, to make graphene oxide, graphite is oxidized in a highly acidic environment. After the oxidation, water is added to dilute the suspension to decrease the acidity.

Note: the full oxidation of every carbon bond on graphite was not able to be achieved.