title: Measuring individual overpotentials in an operating solid-oxide electrochemical cell.
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 H(2)O splitting proceeds more rapidly than H(2) oxidation, while on Pt, H(2) oxidation proceeds more rapidly than H(2)O splitting.
authors.affiliation: Sandia National Laboratories, CA 94550, USA. felgaba@sandia.gov
authors.forename: Farid
authors.initials: F
authors.lastname: El Gabaly
authors.forename: Michael
authors.initials: M
authors.lastname: Grass
authors.forename: Anthony H
authors.initials: AH
authors.lastname: McDaniel
authors.forename: Roger L
authors.initials: RL
authors.lastname: Farrow
authors.forename: Mark A
authors.initials: MA
authors.lastname: Linne
authors.forename: Zahid
authors.initials: Z
authors.lastname: Hussain
authors.forename: Hendrik
authors.initials: H
authors.lastname: Bluhm
authors.forename: Zhi
authors.initials: Z
authors.lastname: Liu
authors.forename: Kevin F
authors.initials: KF
authors.lastname: McCarty