STM

The Influence of Graphene Curvature on Hydrogen Adsorption: Towards

Hydrogen Storage Devices

The realization of new and innovative hydrogen storage materials has worldwide strategic importance. In this context, graphene has recently attracted attention as a promising hydrogen storage medium. Indeed, graphene is lightweight, chemically stable, and exhibits attractive physico-chemical properties for hydrogen adsorption. Furthermore, the interaction between hydrogen and graphene can be controlled by functionalization of the material, thus enabling fine tuning of the adsorption/desorption-properties of hydrogen on graphene. Theoretical studies suggest that graphene can adsorb up to 8 wt% by chemisorption and up to 10 wt% by physisorption of hydrogen. However, experimental demonstrations of these numbers have yet to be reported.

The energetics of the chemisorption of hydrogen on graphene can be modified by the local curvature of the graphene sheet. Based on scanning tunneling microscopy (STM) techniques, we find site-selective adsorption of atomic hydrogen on convexly warped regions of monolayer graphene grown on SiC(0001). This system exhibits an intrinsic curvature owing to the interaction with the substrate [1]. We could show that at low coverage hydrogen is found on convex areas of the graphene lattice. No hydrogen is detected on concave regions. These findings are in agreement with theoretical models which suggest that both binding energy and adsorption barrier can be tuned by controlling the local curvature of the graphene lattice [2]. This curvature-dependence combined with the known graphene flexibility may be exploited for storage and controlled release of hydrogen at room temperature making it a valuable candidate for the implementation of hydrogen-storage devices.

References

    1. S. Goler, C. Coletti, V. Piazza, P. Pingue, F. Colangelo, V. Pellegrini, K. V. Emtsev, S. Forti, U. Starke, F. Beltram, and S. Heun, Carbon 51, 249 (2013).
    2. V. Tozzini and V. Pellegrini, J. Phys. Chem. C 115, 25523 (2011).

Presented at

    1. S. Heun: Graphene as a medium for hydrogen storage, First Scientific Meeting of COST Action 1103, Rome, Italy, 13 - 15 February 2012 (oral). [Talk]
    2. S. Goler: Atomically Resolved Imaging of Hydrogen on Graphene Grown on Silicon Carbide, Graphene Week, Delft, Netherlands, 4 - 8 June 2012 (poster). [Abstract] [Poster]
    3. Massimo Morandini: STM and transport on graphene, Graphene Day, Pisa, Italy, 9 July 2012 (oral). [Talk]
    4. Sarah Goler: Scanning tunnelling microscopy to image the zerolayerof epitaxial graphene grown on SiC(0001), Graphene Day, Pisa, Italy, 9 July 2012 (oral). [Talk]
    5. Torge Mashoff: Functionalized graphene for hydrogen storage, Graphene Day, Pisa, Italy, 9 July 2012 (oral). [Talk]
    6. S. Heun: Hydrogen Storage on Graphene, Keio University, Tokyo, Japan (Dr. Yoshio Watanabe), 27 February 2013. [Abstract] [Talk]
    7. S. Heun: STM Studies of Hydrogen on Graphene, Tokyo University, Japan (Prof. M. Oshima), 28 February 2013. [Abstract] [Talk]
    8. S. Heun: Hydrogen Storage on Graphene: an STM study, NSRRC, Hsinchu, Taiwan (Dr. Chia-Hao Chen), 6 March 2013. [Abstract] [Talk]
    9. S. Heun: The influence of graphene curvature and functionalization on hydrogen adsorption: towards hydrogen storage devices, National Cheng Kung University, Tainan, Taiwan (Prof. Chung-Lin Wu), 8 March 2013. [Abstract] [Talk]
    10. S. Heun: Graphene for Hydrogen Storage, NTT Basic Research Laboratories, Atsugi, Japan (Dr. H. Hibino), 12 March 2013. [Abstract] [Talk]
    11. S. Heun: Hydrogen Storage on Graphene, S3 CNR-Nano, Modena, Italy (Prof. E. Molinari), 15 April 2013. [Abstract] [Talk]

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