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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 (

Though pristine graphene exhibits remarkable mechanical and electronic properties, many electromechanical applications may come from chemically doping it with heteroatoms. The goal is to tune the atomic lattice and, in turn, modulate the electronic band structure of graphene – that may also affect the mechanical responses of the graphene sheet. Particularly essential for both practical applications and fundamental interests is to characterize the effect of chemical doping on the mechanical properties of graphene. Here we report graphene can maintain a large fraction of its pristine strength and stiffness after substituting boron for carbon atoms. Counter-intuitively, boron doping can ameliorate the brittle nature of the original lattice by deflecting the cracks and enabling damage-tolerant behaviors. We further offer a direct mapping between the Raman spectra and the measured mechanical performances that can show the relationship between doping structure and mechanical properties of graphene. This work offers important implications for the rational design of graphene-based systems that require chemical modifications and also utilize the mechanics of graphene.

We systematically investigated the in-plane biaxial compression behavior of the monolayer poly (methyl methacrylate) (PMMA)/graphene/PMMA system by in situ Raman spectroscopy. The shifts of Raman G-band peak position exhibited three-stage features with increasing compressive strain, including elastic deformation, local Euler-buckling and continuous compression. Our results demonstrated that the mechanical stability of graphene based flexible electrodes greatly depended on the deformation modes, applied strain level and interfacial adhesion. The embedded graphene sheets performed reversible compressibility at lower strain level over many cycles. With further increasing compressive strain, the strain distribution of the embedded graphene sheet turned non-uniform, and the interfacial debonding occurred. An analytical model based on the mechanical instability theory was proposed to depict the interfacial debonding behavior of individual graphene sheet, which agreed well with the experimental results.