Journal article
Operando XAS Study of the Surface Oxidation State on a Monolayer IrOx on RuOx and Ru Oxide Based Nanoparticles for Oxygen Evolution in Acidic Media
Department of Physics, Technical University of Denmark1
Neutrons and X-rays for Materials Physics, Department of Physics, Technical University of Denmark2
Surface Physics and Catalysis, Department of Physics, Technical University of Denmark3
Stanford University4
University of Copenhagen5
Stockholm University6
Herein we present surface sensitive operando XAS L-edge measurements on IrOx/RuO2 thin films as well as mass-selected RuOx and Ru nanoparticles. We observed shifts of the white line XAS peak toward higher energies with applied electrochemical potential. Apart from the case of the metallic Ru nanoparticles, the observed potential dependencies were purely core-level shifts caused by a change in oxidation state, which indicates no structural changes.
These findings can be explained by different binding energies of oxygenated species on the surface of IrOx and RuOx. Simulated XAS spectra show that the average Ir oxidation state change is strongly affected by the coverage of atomic O. The observed shifts in oxidation state suggest that the surface has a high coverage of O at potentials just below the potential where oxygen evolution is exergonic in free energy.
This observation is consistent with the notion that the metal-oxygen bond is stronger than ideal.
| Language: | English |
|---|---|
| Publisher: | American Chemical Society (ACS) |
| Year: | 2018 |
| Pages: | 878-887 |
| ISSN: | 15205207 and 15206106 |
| Types: | Journal article |
| DOI: | 10.1021/acs.jpcb.7b06982 |
| ORCIDs: | 0000-0002-6432-3015 , 0000-0001-7749-6567 , Pedersen, Anders Filsøe , Sebok, Bela , Bodin, Anders , Stephens, Ifan , Chorkendorff, Ib and 0000-0003-1968-8696 |
