Amorphous structural models for graphene oxides

Based on the experimental observations, amorphous structural models of graphene oxides (GOs) were constructed and investigated by first-principles computations. Geometric structures, thermodynamic stabilities, and electron density of states of these amorphous GO models were examined and compared with the previously proposed ordered GO structures. The thermodynamically most favorable amorphous GO models always contain some locally ordered structures in the short range, due to a compromise of the formation of hydrogen bonds, the existence of dangling bonds, and the retention of the π bonds. Compared to the ordered counterparts, these amorphous GO structures possess good stability at low oxygen coverage. Varying the oxygen coverage and the ratio of epoxy and hydroxyl groups provides an efficient way to tune the electronic properties of the GO-based materials.