TY - JOUR

T1 - Performance modulation through selective, homogenous surface doping of lanthanum strontium ferrite electrodes revealed by

T2 - In situ PLD impedance measurements

AU - Riedl, Christoph

AU - Siebenhofer, Matthäus

AU - Nenning, Andreas

AU - Friedbacher, Gernot

AU - Weiss, Maximilian

AU - Rameshan, Christoph

AU - Bernardi, Johannes

AU - Limbeck, Andreas

AU - Kubicek, Markus

AU - Opitz, Alexander Karl

AU - Fleig, Juergen

N1 - Publisher Copyright: © 2022 The Royal Society of Chemistry.

PY - 2022/2/14

Y1 - 2022/2/14

N2 - Accelerating the oxygen reduction kinetics of solid oxide fuel cell (SOFC) cathodes is crucial to improve their efficiency and thus to provide the basis for an economically feasible application of intermediate temperature SOFCs. In this work, minor amounts of Pt were doped into lanthanum strontium ferrite (LSF) thin film electrodes to modulate the material's oxygen exchange performance. Surprisingly, Pt was found to be incorporated on the B-site of the perovskite electrode as non metallic Pt4+. The polarization resistance of LSF thin film electrodes with and without additional Pt surface doping was compared directly after film growth employing in situ electrochemical impedance spectroscopy inside a PLD chamber (i-PLD). This technique enables observation of the polarization resistance of pristine electrodes unaltered by degradation or any external contamination of the electrode surface. Moreover, growth of multi-layers of materials with different compositions on the very same single crystalline electrolyte substrate combined with in situ impedance measurements allow excellent comparability of different materials. Even a 5 nm layer of Pt doped LSF (1.5 at% Pt), i.e. a Pt loading of 80 ng cm−2, improved the polarization resistance by a factor of about 2.5. In addition, p(O2) and temperature dependent impedance measurements on both pure and Pt doped LSF were performed in situ and obtained similar activation energies and p(O2) dependence of the polarization resistance, which allow us to make far reaching mechanistic conclusions indicating that Pt4+ introduces additional active sites.

AB - Accelerating the oxygen reduction kinetics of solid oxide fuel cell (SOFC) cathodes is crucial to improve their efficiency and thus to provide the basis for an economically feasible application of intermediate temperature SOFCs. In this work, minor amounts of Pt were doped into lanthanum strontium ferrite (LSF) thin film electrodes to modulate the material's oxygen exchange performance. Surprisingly, Pt was found to be incorporated on the B-site of the perovskite electrode as non metallic Pt4+. The polarization resistance of LSF thin film electrodes with and without additional Pt surface doping was compared directly after film growth employing in situ electrochemical impedance spectroscopy inside a PLD chamber (i-PLD). This technique enables observation of the polarization resistance of pristine electrodes unaltered by degradation or any external contamination of the electrode surface. Moreover, growth of multi-layers of materials with different compositions on the very same single crystalline electrolyte substrate combined with in situ impedance measurements allow excellent comparability of different materials. Even a 5 nm layer of Pt doped LSF (1.5 at% Pt), i.e. a Pt loading of 80 ng cm−2, improved the polarization resistance by a factor of about 2.5. In addition, p(O2) and temperature dependent impedance measurements on both pure and Pt doped LSF were performed in situ and obtained similar activation energies and p(O2) dependence of the polarization resistance, which allow us to make far reaching mechanistic conclusions indicating that Pt4+ introduces additional active sites.

UR - http://www.scopus.com/inward/record.url?scp=85124616221&partnerID=8YFLogxK

U2 - 10.1039/d1ta08634k

DO - 10.1039/d1ta08634k

M3 - Article

AN - SCOPUS:85124616221

VL - 10.2022

SP - 2973

EP - 2986

JO - Journal of Materials Chemistry A

JF - Journal of Materials Chemistry A

SN - 2050-7488

IS - 6

ER -