AVS 66th International Symposium & Exhibition
    Frontiers of New Light Sources Applied to Materials, Interfaces, and Processing Focus Topic Thursday Sessions
       Session LS+AS+SS-ThM

Invited Paper LS+AS+SS-ThM1
X-Ray Insight into Fuel Cell Catalysis: Operando Studies of Model Surfaces and Working Devices

Thursday, October 24, 2019, 8:00 am, Room A124-125

Session: Operando Methods for Unraveling Fundamental Mechanisms in Devices Towards Renewable Energies
Presenter: Jakub Drnec, European Synchrotron Radiation Facility, France
Authors: J. Drnec, European Synchrotron Radiation Facility, France
I. Martens, European Synchrotron Radiation Facility, France
T. Fuchs, University of Kiel, Germany
T. Wiegmann, European Synchrotron Radiation Facility, Germany
A. Vamvakeros, Finden Ltd., UK
R. Chattot, European Synchrotron Radiation Facility, France
O.M. Magnussen, University of Kiel, Germany
Correspondent: Click to Email
Complete physico-chemical operando characterization of electrochemical devices in whole, or it’s constituent materials separately, is necessary to guide the development and to improve the performance. High brilliance synchrotron X-ray sources play a crucial role in this respect as they act as a probe with relatively high penetration power and low damage potential. In this contribution the new possibilities of using using high energy, high intensity X-rays to probe model fuel cell catalysts and energy conversion devices will be presented.

HESXRD (High Energy Surface X-ray Diffraction) [1] and TDS (Transmission Surface Diffraction) [2] provide ideal tools to study structural changes during reaction conditions on single crystal model electrodes. The main advantage of both techniques is the possibility to follow the structural changes precisely with atomic resolution. While HESXRD is ideally used to determine exact atomic position, the TSD is easier to use and allows studies with high spatial resolution. For example, HESXRD can be used to follow the atomic movement of Pt atoms during electrochemical oxidation and dissolution with very high precision, explaining the different catalyst degradation behaviors and suggesting possible routes to improve its durability [3-4]. The TSD is an excellent tool to study advanced 2D catalysts.

To study fuel cells or batteries as a whole, elastic scattering techniques, such as WAXS and SAXS, can be employed as they can provide important complementary information to more standard X-ray imaging and tomography. The advantage is that the chemical contrast and sensitivity at atomic and nm scales is superior. Coupling these technique with the tomographic reconstruction (XRD-CT and SAXS-CT) is much less common as it requires bright synchrotron sources and advanced instrumentation, but allows 3D imaging of operational devices with unprecedented chemical sensitivity. This can be demonstrated on imaging of standard 5 cm2 fuel cells during operation. The change in morphology and atomic arrangement of the catalysts, PEM hydration and water distribution can be followed in one experiment as a function of operating conditions. Furthermore, the fundamental processes leading to the catalyst aging can be assessed with high temporal and spatial resolution. These advanced scattering techniques open a door to holistic investigations of operational devices, which are needed to successfully incorporate new materials at the device level.

[1] J. Gustafson et al., Science 343, 758 (2014)

[2] F. Reikowski et al., J. Phys. Chem. Lett., 5, 1067-1071 (2017)

[3] J. Drnec et al, Electrochim. Acta, 224 (2017),

[4] Chattot et al., Nature Materials, 17(2018)