Fatigue resistance of atomically thin graphene oxide

Abstract

Under cyclic loading, while graphene can suffer from catastrophic brittle fatigue failure, graphene oxide (GO) can be engineered to improve fatigue response and possibly ductile failure. Herein, we study the fatigue response of atomically thin GO using atomistic simulations complemented by atomic force microscopy-based experiments. Analysis of the damage and failure mechanisms demonstrated a notable role of functionalization degree and ratio on the fatigue resistance of GO. In the presence of defects, GO with a low functionalization degree (<15%) exhibited a low defect sensitivity and considerably high fatigue life compared to graphene. Although a reduction in the lifetime was captured for higher functionalization degrees, enhancement in fatigue resistance was observed for epoxy-rich GO, owing to an effective crack arresting mechanism by first epoxy-to-ether transformations of the ether groups and ether-to-epoxy retransformations during loading and unloading phases of a cycle respectively, unearthed using nudged elastic band calculations. Present findings reveal molecular engineering of functional groups as a tool to tune the fatigue resistance of GO and potentially other nanomaterials, paving the way for the design of nanodevices and nanostructured materials with superior durability.