Measuring individual overpotentials in an operating solid-oxide electrochemical cell
By El Gabaly, Farid; Grass, Michael; McDaniel, Anthony H.; Farrow, Roger L.; Linne, Mark A.; Hussain, Zahid; Bluhm, Hendrik; Liu, Zhi & McCarty, Kevin F.
Published in Phys. Chem. Chem. Phys.
The Royal Society of Chemistry
2010
Abstract
We use photo-electrons as a non-contact probe to measure local electrical potentials in a solid-oxide electrochemical cell. We characterize the cell in operando at near-ambient pressure using spatially-resolved X-ray photoemission spectroscopy. The overpotentials at the interfaces between the Ni and Pt electrodes and the yttria-stabilized zirconia (YSZ) electrolyte are directly measured. The method is validated using electrochemical impedance spectroscopy. Using the overpotentials, which characterize the cell ' s inefficiencies, we compare without ambiguity the electro-catalytic efficiencies of Ni and Pt, finding that on Ni H2O splitting proceeds more rapidly than H2 oxidation, while on Pt, H2 oxidation proceeds more rapidly than H2O splitting.