Evolution of layer distance and structural arrangement of graphene oxide with various oxygen content and functional types in low temperature: A ReaxFF molecular dynamics simulation

Due to the oxygen-containing functional groups covering the graphene oxide surface, multilayer graphene oxide has different properties. The understanding of its atomic structure and layer stacking behavior at low temperature is far from complete. This work systematically revealed how the oxygen-containing groups density, type and temperature affect the spacing of multilayer GO layers through the ReaxFF molecular dynamics simulation method. We found that the density of oxygen-containing groups is the main variable that controls the distribution of surface oxidation areas and the degree of distortion of the graphene sheets. With the increase of C/O ratio, the distribution of oxygen-containing functional groups tends to aggregate, and the deformation of graphite flakes becomes more serious. The layer spacing of multilayer GO is affected by temperature. The types of released small molecules, the degree of pyrolysis of the graphene skeleton and the interlayer spacing are all affected by OH/O ratio. With more hydroxyl groups, it is easier to release long O-H chains, and the graphene skeleton is less likely to be pyrolyzed. This in-depth investigation has helped develop a fundamental understanding of the atomic structure of graphene oxide and has laid basic foundations for an effective control of graphene layer distance and properties.