A spectroscopic proton-exchange membrane fuel cell test setup allowing fluorescence x-ray absorption spectroscopy measurements during state-of-the-art cell tests

Abstract

A test setup for membrane-electrode-assemblies (MEAs) of proton exchange membrane fuel cells which allows in situ fluorescence x-ray absorption spectroscopy studies of one electrode with safe exclusion of contributions from the counter electrode is described. Interference by the counter electrode is excluded by a geometry including a small angle of incidence (< 6°) between primary beam and electrode layer. The cell has been constructed by introducing just minor modifications to an electrochemical state-of-the-art MEA test setup, which ensures realistic electrochemical test conditions. This is at the expense of significant intensity losses in the path of the incident beam, which calls for the brilliance of third-generation synchrotrons to provide meaningful data. In measurements on Pt∕C and Pt-Co∕C cathodes combined with Pt-C anodes (H(2)/O(2) feed), good data quality was demonstrated both for the majority element Pt as well as for Co despite of a low areal Co density in the order of 0.02 mg/cm(2).

Potential-Dependent Restructuring and Hysteresis in the Structural and Electronic Transformations of Pt/C, Au(Core)-Pt(Shell)/C, and Pd(Core)-Pt(Shell)/C Cathode Catalysts in Polymer Electrolyte Fuel Cells Characterized by in Situ X-ray Absorption Fine Structure

“…X-ray absorption fine structure (XAFS) analysis has become a powerful tool for investigating the local coordination structures and oxidation states of supported metal nanoparticle catalysts under in situ reaction conditions. ,,− The mechanisms of the electrochemical processes involved in rapid voltage-controlled processes on Pt/C and Pt 3 Co/C catalysts have been investigated by a real-time XAFS technique, showing the kinetics and rate constants of elementary reaction steps for structural and electronic transformations of the cataysts. , In the present study we report new aspects of the restructuring and hysteresis in the transformations of surface structures, Pt oxidation states, and Pt–O bondings of the Pt/C, Au(core)-Pt(shell)/C (denoted as Au@Pt/C), and Pd(core)-Pt(shell)/C (denoted as Pd@Pt/C) cathode catalysts in PEFC MEAs during the voltage-stepping processes based on a systematic molecular-level study by in situ (operando) XAFS.…”

In SituCharacterization of Ni and Ni/Fe Thin Film Electrodes for Oxygen Evolution in Alkaline Media by a Raman-Coupled Scanning Electrochemical Microscope Setup

“…However, it is a well-known fact from catalysis and electrocatalysis research that catalyst materials change during operation. , Thus, to fully understand the behavior of electrocatalysts, in situ studies are necessary to unravel structural changes and concomitant changes in activity of the material under investigation to complement the above-mentioned approaches. Indeed, a broad variety of techniques, including X-ray diffraction, X-ray absorption, , X-ray photoelectron, infrared (IR), and Raman spectroscopy, were successfully applied to the in situ study of electrocatalysts. Although these techniques provide indispensable information on structure, structural changes and resulting electrochemical performance of catalysts, it might be considered a drawback that spectroscopic information is typically obtained from a certain location of the electrode, while the electrochemical experiment probes the whole sample.…”

Electrochemical Flow-Cell Setup for In Situ X-ray Investigations

“…[10][11][12][13] Electrochemical cells for in situ X-ray spectroscopy studies of electrocatalysts have been published based on a PEFC-type design with a non-liquid polymer electrolyte. [14][15][16][17] Although for PEFC-related catalyst investigations such setups are advantageous, their use remains restricted to available polymer electrolytes. Especially for studies in alkaline environment, a cell design for liquid electrolytes is desirable.…”