Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 57: Solid / liquid interfaces II

O 57.3: Talk

Wednesday, March 28, 2012, 17:15–17:30, A 060

Electrocatalytic activity of small Pt nanoparticles on monolayer graphene supported by Ru(0001) — •Christoph U. Lorenz, Otavio B. Alves, and R. Jürgen Behm — Ulm University, D-89069 Ulm, Germany

With their characteristic Moiré-type nm-scale superstructure, graphene monolayers supported on metal single crystals [1,2] can serve as ideal, chemically inert template for the growth of ordered arrays of very small nano-sized metallic (electro-)catalyst particles. For Pt deposition on gr/Ru(0001), particles fabricated by metal vapor deposition under ultrahigh vacuum conditions, displayed heights of a few layers and lateral diameters in the range of 1-2 nm as measured by STM [3,4]. Based on their narrow size distribution and their regular arrangement, these Pt nanoparticles appear as interesting and promising system for (electro-)catalytic model studies. Cluster arrays with different Pt coverages and cluster size distributions, which were determined by STM, were tested as electrodes for elementary reactions such as hydrogen evolution/oxidation, CO oxidation, and O2 reduction. Potential-dependent reaction rates were measured in a wall-jet type flow cell located in an electrochemical pre-chamber attached to the main UHV system. The electrochemical behavior of the Pt cluster arrays will be discussed in comparison to bulk Pt and realistic carbon supported Pt catalysts. [1] C. Oshima et al., J. Phys. Condens. Matter 9, 1 (1997). [2] S. Marchini et al., Phys. Rev. B 76, 075429 (2007). [3] N'Diaye et al., New J. Phys. 11, 103045 (2009). [4] K. Donner & P. Jakob, J. Chem. Phys. 131,164701 (2009).