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Operando SAXS Study of a Pt/C Fuel Cell Catalyst with an X-ray Laboratory Source

preprint
submitted on 24.03.2021, 10:06 and posted on 26.03.2021, 07:49 by Johanna Schröder, Jonathan Quinson, Jacob J. K. Kirkensgaard, Matthias Arenz
Small angle X-ray scattering (SAXS) is a powerful technique to investigate the degradation of catalyst materials. Ideally such investigations are performed operando, i.e., during a catalytic reaction. An example of operando measurements is to observe the degradation of fuel cell catalysts during an accelerated stress test (AST). Fuel cell catalysts consist of Pt or Pt alloy nanoparticles (NPs) supported on a high surface area carbon. A key challenge of operando SAXS measurements is a proper background subtraction of the carbon support to extract the information of the size distribution of the Pt NPs as a function of the AST treatment. Typically, such operando studies require the use of synchrotron facilities. The background measurement can then be performed by anomalous SAXS (aSAXS) or in a grazing incidence con-figuration. In this work we present a proof-of-concept study demonstrating the use of a laboratory X-ray diffractometer for operando SAXS. Data acquisition of operando SAXS with a laboratory X-ray diffractometer is desirable due to the general challenging and limited accessibility of synchrotron facilities. They become even more crucial under the ongoing and foreseen restrictions related to the COVID-19 pandemic. Although, it is not the aim to completely replace synchrotron-based studies, it is shown that the background subtraction can be achieved by a simple experimental consideration in the setup that can ultimately facilitate operando SAXS measurements at a synchrotron facility.

Funding

Swiss National Science Foundation (SNSF) via the project No. 200021_184742

Danish National Research Foundation Center for High En-tropy Alloys Catalysis (CHEAC) DNRF-149

History

Email Address of Submitting Author

johanna.schroeder@dcb.unibe.ch

Institution

University of Bern

Country

Switzerland

ORCID For Submitting Author

0000-0001-5461-4751

Declaration of Conflict of Interest

No conflict of interest.

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