Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 82: Metal Substrates II

O 82.11: Vortrag

Donnerstag, 3. April 2014, 18:30–18:45, WIL A317

Spontaneous step creation during NO reduction on Pt surfaces: a high-pressure STM study — •Matthijs van Spronsen, Qian Liu, and Joost Frenken — Kamerlingh Onnes Laboratory, Leiden University, Leiden, P.O. Box 9504, 2300 RA, The Netherlands

When atoms and molecules adsorb on surfaces, they can introduce significant changes in the surface stress, for example when an overlayer is formed of dipolar molecules that strongly repel each other. This may have dramatic consequences for the structure of catalysts that have dense overlayers due the to high gas pressures. We have used a scanning tunneling microscope (STM), dedicated for atomic-scale, high-pressure, high-temperature observations of active catalysts, to investigate the structural changes that occur on a Pt(110) surface when this is active as a catalyst for NO reduction by H2. To our surprise we find that atmospheric pressures of (NO,H2) gas mixtures lead to the spontaneous creation of regular step arrays on the initially flat surface. We propose that the step creation is a pathway for the surface to relax part of the high, adsorption-induced stress. This interpretation finds support in DFT calculations.