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O: Fachverband Oberflächenphysik
O 68: Metal Substrates: Solid-Liquid Interfaces
O 68.2: Talk
Thursday, February 28, 2008, 13:30–13:45, MA 043
Electrochemical oxygen reduction at pseudomorphic Pt thin films on Ru(0001) — •Otávio B. Alves, Harry E. Hoster, and R. Jürgen Behm — Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm, Germany
We report on the electrochemical properties of model surfaces consisting of 1-5 pseudomorphic Pt layers on Ru(0001), which are fabricated by vapor deposition under ultrahigh vacuum conditions. Due to electronic ligand and strain effects, the interaction of these surfaces with Had, OHad, and Oad is weakened compared to Pt(111). According to theoretical predictions,[1,2] this can lead to a higher activity for the electrochemical reduction of oxygen, similar to the behavior previously reported for Pt3Ni model electrodes.[3] By changing the layer thickness, it is possible to tune the adsorption properties within a certain range.[4] We investigated the oxygen reduction current as a function of potential under well-defined mass transport conditions for all model surfaces in an electrochemical flow cell coupled to a UHV system. The electrochemical behaviour of the pseudomorphic Pt films was found to be clearly different from that of Pt(111). The results are discussed in comparison to the behavior of other model electrodes and to theoretical predictions.
[1] M. Mavrikakis et al., Phys. Rev. Lett. 1998, 81, 2819.
[2] J. R. Kitchin et al., J. Chem. Phys. 2004, 120, 10240.
[3] V. R. Stamenkovic et al., Science 2007, 315, 493.
[4] A. Schlapka et al., Phys. Rev. Lett. 2003, 91, 016101.