Regensburg 2013 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
O: Fachverband Oberflächenphysik
O 8: Surface Chemical Reactions and Heterogeneous Catalysis I
O 8.11: Talk
Monday, March 11, 2013, 13:00–13:15, H33
Auto-catalytic creation of active sites?! Step formation during NO reduction at Pt(110) — •Tongyu Wang1, Qian Liu2, Joost W.M. Frenken2, and Karsten Reuter1 — 1TU München, Germany — 2Leiden University, The Netherlands
We report a surprisingly distinct faceting of Pt(110) into vicinal orientations with highly regular step lattices during the near-ambient NO reduction by H2. Reactor Scanning Tunneling Microscopy (STM) measurements demonstrate that the step density can be reversibly tuned by the NO/H2 partial pressure ratio. In view of the potential role of steps in the reaction, this could reflect a unique self-promoting feature. We analyze these observations through first-principles atomistic thermodynamics calculations. They predict the formation of a high-coverage NO phase precisely over the experimentally employed (T,p)-range. Surface stress calculations show that the highly repulsive interaction in this adlayer builds up a huge compressive stress. This stress is accommodated by the expansive, lateral relaxation that the Pt surface can perform, when either space (grooves) or ’overhang’-type geometries (steps) are created. We thus suggest surface stress relaxation as atomic-scale origin behind the observed faceting.