Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 50: Graphene (organized by O)

TT 50.20: Poster

Dienstag, 17. März 2015, 18:15–21:00, Poster A

Water chemistry beneath graphene: Formation and breathing of a super-dense OH-H2O phase under grapheneElin Grånäs1, •Ulrike A. Schröder2, Mohammad A. Arman1, Mie Andersen3, Timm Gerber2, Karina Schulte4, Jesper N. Andersen1,4, Thomas Michely2, Bjørk Hammer3, and Jan Knudsen1,41Division of Synchrotron Radiation Research, Lund University, Sweden — 2II. Physikalisches Institut, Universität zu Köln, Germany — 3Interdisciplinary Nanoscience Center and Department of Physics and Astronomy, Aarhus University, Denmark — 4MAX IV Laboratory, Lund University, Sweden

Placing catalysts in confined environments, e.g. carbon nanotubes, is a powerful method to modify their activity or selectivity. Unfortunately, atomic level understanding of the confinement effects is hindered by the complexity of these materials.

We use Ir(111)-supported graphene (Gr) flakes to study room temperature reduction of atomic oxygen in a confined 2D nano-reactor with X-ray photoelectron spectroscopy and scanning tunneling microscopy. The Gr cover can be used to trap OH-H2O phases that otherwise would desorb directly. Our study of these Gr-stabilized phases and their response to oxygen and hydrogen exposure reveals 2D breathing of a O-OH-H2O phase as O-atoms are dissolved into the structure (expansion) and subsequently converted to OH and H2O (contraction). Using density functional theory calculations combined with a genetic search algorithm, the structure and stability of the trapped OH-H2O structures were determined.

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DPG-Physik > DPG-Verhandlungen > 2015 > Berlin