Density functional theory study of graphite oxide for different oxidation levels

Graphite oxide constitutes a hexagonal carbon network with oxygen atoms in carbon-oxide ether ring formations and hydroxyl molecules. We have studied graphite oxide with a first-principles density functional theory calculation for different oxidation levels. The oxygen atoms form 1,2-ether groups (epoxides) on the carbon grid, with on the adjacent carbon atoms, but at the opposite side of the carbon plane, the hydroxyl molecules. Graphite oxide cannot have 1,3-ether oxygens because of the higher formation energy. The transverse wrinkling of the carbon grid is about 0.5 A, mostly due to the deformation around the hydroxyl bonds, yet the in-plane lattice axes retain the hexagonal features of graphene. A stable graphite oxide structure requires hydroxyl molecules to relax the tension on the carbon grid from the 1,2-ether oxygens. At a low degree of oxidation, graphite oxide is a semiconductor, but when the oxidation is saturated, it turns into an insulator.