Elastic properties of chemically derived single graphene sheets

Max-Planck-Institut fur Festkorperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany.
Nano Letters (Impact Factor: 12.94). 08/2008; 8(7):2045-9. DOI: 10.1021/nl801384y
Source: PubMed

ABSTRACT The elastic modulus of freely suspended graphene monolayers, obtained via chemical reduction of graphene oxide, was determined through tip-induced deformation experiments. Despite their defect content, the single sheets exhibit an extraordinary stiffness ( E = 0.25 TPa) approaching that of pristine graphene, as well as a high flexibility which enables them to bend easily in their elastic regime. Built-in tensions are found to be significantly lower compared to mechanically exfoliated graphene. The high resilience of the sheets is demonstrated by their unaltered electrical conductivity after multiple deformations. The electrical conductivity of the sheets scales inversely with the elastic modulus, pointing toward a 2-fold role of the oxygen bridges, that is, to impart a bond reinforcement while at the same time impeding the charge transport.

  • [Show abstract] [Hide abstract]
    ABSTRACT: High level of reinforcement is observed in ceramic matrix composites containing multilayer graphene, which is frequently attributed to bridging and pull-out phenomena based on microstructural observations of crack paths. Presently, we show that the toughening level observed in two ceramic matrix composites with different graphene type fillers is reasonably fitted to the well-known model for reinforcement of ceramic composites by whiskers/fibers. Furthermore, the most important toughening contribution for these composites is due to bridging by the graphene fillers. The model predicts a steady toughness increment as a function of filler volume but for filler volume concentrations close to the percolation threshold the experimentally observed reinforcement deviates from the model predictions and toughness starts to decay. Consequently, once graphene fillers are fully connected forming a three dimensional network bridging the graphene fillers stops being an effective toughening mechanism.
    Ceramics International 08/2014; 40(7):11187-11192. DOI:10.1016/j.ceramint.2014.03.150 · 2.09 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Nano-tribological properties of graphene have attracted a lot of research interest in the last few years. In this work, X-ray photoelectron spectroscopy was used to study the distribution of chemical groups in chemical vapor deposition (CVD) of single layer graphene transferred onto a 90 nm SiO2/Si substrate. It was demonstrated that the graphene was oxidized after thermal treatment at 520 degrees C in ambient air, as indicated by the formation of C = O and C-OH bonds. Significantly enhanced D-band and decreased 2D-band were found in the Raman spectrum. Blue shift occurred for the G-band and 2D-band after thermal oxidation. The nano-tribological properties of graphene before and after thermal oxidation were studied with atomic force microscopy. A remarkable increase of friction was found on the surface of graphene after thermal oxidation. This was contributed to by the increased adhesion and decreased Young's modulus of the functionalized graphene, inducing the increase of contact stiffness. In addition, the adhesion force between the tip and the samples was discussed as an important factor affecting tribological properties on the nano-scale.
    RSC Advances 01/2015; 5(13). DOI:10.1039/C4RA12437E · 3.71 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Discovery of graphene and its astonishing properties have given birth to a new class of materials known as “2D materials”. Motivated by the success of graphene, alternative layered and non-layered 2D materials have become the focus of intense research due to their unique physical and chemical properties. Origin of these properties ascribed to the dimensionality effect and modulation in their band structure. This review highlights the recent progress of the state-of-the-art research on synthesis, characterization and isolation of single and few layer nanosheets and their assembly. Electronic, magnetic, optical and mechanical properties of 2D materials have also been reviewed for their emerging applications in the area of catalysis, electronic, optoelectronic and spintronic devices; sensors, high performance electrodes and nanocomposites. Finally this review concludes with a future prospective to guide this fast evolving class of 2D materials in next generation materials science.
    Progress in Materials Science 03/2015; DOI:10.1016/j.pmatsci.2015.02.002 · 25.87 Impact Factor


Available from