Dresden 2020 – wissenschaftliches Programm
Die DPG-Frühjahrstagung in Dresden musste abgesagt werden! Lesen Sie mehr ...
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 67: Solid-Liquid Interfaces III: OER, ORR, CO2RR, etc.
O 67.5: Vortrag
Mittwoch, 18. März 2020, 11:45–12:00, WIL C107
Effect of electric field on oxygen reduction kinetics at the Pt(111), Au(111) and Au(100) electrodes — •Sara Kelly1, Charlotte Kirk1, Karen Chan2, and Jens Nørskov2 — 1SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States — 2Department of Physics, Technical University of Denmark, Building 311, DK-2800 Lyngby, Denmark
Microkinetic modeling of the oxygen reduction reaction (ORR) has thus far failed to predict dependence of this reaction on pH on several important catalysts. In this work, we create a new microkinetic model for the ORR which incorporates field effects into the established computational hydrogen electrode (CHE) model. We find that field can significantly alter the binding energy of the *O2, *OOH, and *H2O2 adsorbates. By considering these effects, we find that we can accurately reproduce experimental polarization curves and rotating ring disk electrode (RRDE) currents on Pt(111), Au(111), and Au(100) electrodes, allowing us to predict both overall ORR activity and selectivity toward hydrogen peroxide. We then use these predictions to better understand activity and selectivity of ORR catalysts and how each of these depends on pH. We show that hydrogen peroxide selectivity depends mainly on the binding energy of *H2O2 relative to that of *OOH. Finally, we argue that considering field effects can expand the search for improved ORR catalysts by allowing us to deconvolute the activity dependence of catalysts on the standard hydrogen electrode (SHE) and the reversible hydrogen electrode (RHE).