Regensburg 2019 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 13: Solid-Liquid Interfaces I: Electrocatalysis and Photoelectrochemistry

O 13.6: Vortrag

Montag, 1. April 2019, 16:15–16:30, H16

Kinetic and transport effects in the ORR on Pt/Ru(0001) model catalysts — •Albert K. Engstfeld, Klein Jens, Fuchs Stefan, Jusys Zenonas, and R.Jürgen Behm — Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm

The efficiency of a fuel cell (fueled with, e.g., H2, MeOH) could be enhanced by decreasing the overpotential for the oxygen reduction reaction (ORR) at the cathode at low current densities (kinetic limitations). At high overpotentials (high current densities), the reaction is mass transport limited and thus only depends on the geometric arrangement as well as the loading of the active catalyst material. In this work, we report on the ORR on monolayer high Pt island modified Ru(0001) model electrodes. The surfaces are prepared and characterized by STM under UHV conditions, while the electrocatalytic investigation is performed in an electrochemical flow cell system attached to the main UHV system.[1] We will first discuss the influence of the Pt coverage on the kinetic currents and show that electrodes with high Pt coverages are more active than bare Pt(111). Second, we demonstrate that at high overpotentials electrodes with low Pt coverages show a much larger turn-over frequency per Pt atom compared to high Pt coverages. Finally, we observed that our model catalyst also forms significant amounts of H2O2. Possible reasons will be discussed in relation to the structural properties of the electrodes. [1] Schnaid, Beckord, Engstfeld, Klein, Brimaud, Behm, PCCP 19 (2017) 4166