(706f) Graphene Oxide Model Development Via Reactive Molecular Dynamics Simulations

The properties of graphene oxide (GO) are largely depending on the coexistence of hybridized carbon atoms, the diversity of oxygen-containing functional groups, and the structural defects. It is of vital importance to develop atomic graphene oxide model, which in turn enables the construction of structure-property relationship, as well as the design and upgrade of graphene oxide-based applications. Despite the efforts of graphene oxide model development over the last decade, there is no atomic GO model available, capturing all key characteristics of experimental GO samples, namely, the hybridization and distribution of carbon atoms, the C/O ratio, the size and distribution of vacancy defects. In this work, we carried out temperature-programmed reactive molecular dynamic simulations (RxMD) to generate atomistic graphene oxide models. By a systematical study of three controlling parameters: the initial functionalization density, the ratio of basal hydroxyl and epoxy groups, and the annealing trigger temperature, we propose an atomic GO model that is representative of the GO product via the modified Hummer method. The atomistic GO models have been analyzed and compared with available experimental results of Fourier-transform infrared spectroscopy (characteristic functional groups), X-ray photo-electron spectroscopy (hybridization and distribution of carbon atoms), and atomic force microscopy (thickness of curved GO). The new model provides insight specifically for GO membrane development and applications.