Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 20: Solid-Liquid Interfaces: Reactions and Electrochemistry - Experiment I
O 20.7: Vortrag
Montag, 20. März 2017, 18:00–18:15, WIL B321
Live, in situ STM observation of the oxidative roughening of Pt(111) — •Leon Jacobse1, Yi-Fan Huang1, Marcel J. Rost2, and Marc T.M. Koper1 — 1Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands — 2Huygens-Kamerlingh Onnes Laboratory, Leiden University, Leiden, The Netherlands
Platinum nanoparticles are used in a wide variety of catalytic processes. In many of these applications, e.g. the anodes of fuel cells, the platinum surface is (partly) oxidized. It is known that by oxidizing and reducing platinum electrochemically, its surface structure is altered, which plays a role in the degradation of the catalyst. However, even for well-defined single crystal surfaces, over thirty years of research did not yet yield a conclusive description of this process on the atomic level.
Using our high-speed, electrochemical scanning tunneling microscope (EC-STM) we continuously oxidized and reduced the surface while simultaneously imaging the surface on the atomic level during the full potential sweep. This provides us with unique information, from which we directly can correlate the changes in surface structure to the changes in the cyclic voltammetry. The formation of nanoscale islands, upon oxidizing and reducing the surface, goes hand in hand with an increase in the current related to hydrogen desorption from step edges. Surprisingly, the development of these islands seems to continue on much longer timescales than suggested in literature, where the evolution of the surface structure was studied in great detail by cyclic voltammetry.[1]
[1] e.g. Electrochim. Acta 2012, 82 (0), 558-569.