New XAFS beamline for structural and electronic dynamics of nanoparticle catalysts in fuel cells under operating conditions

Sekizawa, Oki; Uruga, Tomoya; Tada, Mizuki; Nitta, Kiyofumi; Kato, Kazúo; Tanida, Hajime; Takeshita, Kunikazu; Takahashi, Sunao; Sano, Mutsumi; Aoyagi, H.; Watanabe, Atsuo; Nariyama, Nobuteru; Ohashi, Haruhiko; Yumoto, Hirokatsu; Koyama, Takahisa; Senba, Yasunori; Takeuchi, Tomoyuki; Furukawa, Yukito; Ohata, T.; Matsushita, Teruo; Ishizawa, Yasuhide; Kudo, Togo; Kimura, H.; Yamazaki, Hiroshi; Tanaka, Takashi; Bizen, Teruhiko; Seike, T.; Goto, Shunji; Ohno, Hideo; Takata, Masaki; Kitamura, Hideo; Ishikawa, Tetsuya; Yokoyama, Toshihiko; Iwasawa, Yasuhiro

doi:10.1088/1742-6596/430/1/012020

Cited by 28 publications

(17 citation statements)

References 3 publications

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“…Experimental procedure schematics, TEM, STEM-EDS, XANES, EXAFS curve-fitting results, series of time-resolved XANES spectra and EXAFS Fourier transforms, the analysis of structural parameters, and complete citations for refs and (PDF)…”

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confidence: 99%

Kinetics and Mechanism of Redox Processes of Pt/C and Pt₃Co/C Cathode Electrocatalysts in a Polymer Electrolyte Fuel Cell during an Accelerated Durability Test

et al. 2016

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The degradation of Pt electrocatalysts in membrane electrode assemblies (MEAs) of polymer electrolyte fuel cells under working conditions is a serious problem for their practical use. Here we report the kinetics and mechanism of redox reactions at the surfaces of Pt/C and Pt3Co/C cathode electrocatalysts during catalyst degradation processes by an accelerated durability test (ADT) studied by operando time-resolved X-ray absorption fine structure (XAFS) spectroscopy. Systematic analysis of a series of Pt LIII-edge time-resolved XAFS spectra measured every 100 ms at different degradation stages revealed changes in the kinetics of Pt redox reactions on Pt/C and Pt3Co/C cathode electrocatalysts. In the case of Pt/C, as the number of ADT cycles increased, structural changes for Pt redox reactions (charging, surface, and subsurface oxidation) became less sensitive because of the agglomeration of catalyst particles. It was found that their rate constants were almost constant independent of the agglomeration of the Pt electrocatalyst. On the other hand, in the case of Pt3Co/C, the rate constants of the redox reactions of the cathode electrocatalyst gradually reduced as the number of ADT cycles increased. The differences in the kinetics for the redox processes would be differences in the degradation mechanism of these cathode electrocatalysts.

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confidence: 99%

Kinetics and Mechanism of Redox Processes of Pt/C and Pt₃Co/C Cathode Electrocatalysts in a Polymer Electrolyte Fuel Cell during an Accelerated Durability Test

et al. 2016

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“…[7,18] X-rays from an undulator were monochromatized by a Si(111) monochromator and then horizontally and vertically focused by KB mirrors (Figure 1). [7,18] X-rays from an undulator were monochromatized by a Si(111) monochromator and then horizontally and vertically focused by KB mirrors (Figure 1).…”

Section: Methodsmentioning

confidence: 99%

“…Scanning nano-XRF and nano-XAFS measurements were conducted at the BL39XU and BL36XU beamlines at SPring-8. [7,18] X-rays from an undulator were monochromatized by a Si(111) monochromator and then horizontally and vertically focused by KB mirrors (Figure 1). The working distance from the edge of the KB mirror case to the focal point was 85 mm (BL39XU/BL36XU).…”

Section: Methodsmentioning

confidence: 99%

“…Scanning nanobeam X-ray fluorescence (nano-XRF) and nano-XAFS were conducted at the BL39XU and BL36XU beamlines of SPring-8, using nano-focusing optics including KB mirrors ( Figure 1). [7,18] Nano-XRF 2D mapping images were obtained by scanning the membrane horizontally and vertically using a piezoelectric stage and by recording the entire range of Ce La fluorescent X-rays (4.62-5.04 keV) that emitted upon X-ray excitation of the Pt/CZ-x particles at intervals of 90 or 45 nm. Space-resolved Ce L III -edge nano-XAFS spectra were obtained by correcting the XRF 2D mapping images at each of the excitation energy points in the range 5.6500 to 5.8000 keV.…”

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Visualization of the Heterogeneity of Cerium Oxidation States in Single Pt/Ce₂Zr₂O_x Catalyst Particles by Nano‐XAFS

et al. 2014

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The cerium oxidation states in single catalyst particles of Pt/Ce2Zr2O(x) (x=7 to 8) were investigated by spatially resolved nano X-ray absorption fine structure (nano-XAFS) using an X-ray nanobeam. Differences in the distribution of the Ce oxidation states between Pt/Ce2Zr2O(x) single particles of different oxygen compositions x were visualized in the obtained two-dimensional X-ray fluorescent (XRF) mapping images and the Ce L(III)-edge nano X-ray absorption near-edge structure (nano-XANES) spectra.

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“…This beamline initially targets the study of nanosized cathode materials for a polymer electrolyte fuel cell (PEFC). 114,115 For example, the active Pt species in PEFC can be mapped. 116 Some significant challenges in thoroughly and fundamentally understanding the chemistry of various zeolite catalyzed reactions may be genuinely tackled with such an experimental setup.…”

Section: State-of-the-art Developmentmentioning

confidence: 99%

The Contribution of Synchrotron X-Ray Powder Diffraction to Modern Zeolite Applications: A Mini-review and Prospects

Tsang

2018

Chem

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Synchrotron X-ray powder diffraction has begun to stretch its strategic presence from the sheer determination of crystal structures into the mechanistic and kinetic information of microporous zeolite materials. Not only can this technique be used to reveal the internal framework structure of zeolites and their active sites, but it can also be combined with other analytical tools to suit the particular needs for in situ or operando gas storage and separation and catalytic studies. This review covers the recent development of using synchrotron X-ray powder diffraction as the primary tool for the study of fundamental interactions with organic molecules with active sites in powder zeolites, as well as some perspectives based on this experimental capability.

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New XAFS beamline for structural and electronic dynamics of nanoparticle catalysts in fuel cells under operating conditions

Cited by 28 publications

References 3 publications

Kinetics and Mechanism of Redox Processes of Pt/C and Pt₃Co/C Cathode Electrocatalysts in a Polymer Electrolyte Fuel Cell during an Accelerated Durability Test

Kinetics and Mechanism of Redox Processes of Pt/C and Pt₃Co/C Cathode Electrocatalysts in a Polymer Electrolyte Fuel Cell during an Accelerated Durability Test

Visualization of the Heterogeneity of Cerium Oxidation States in Single Pt/Ce₂Zr₂O_x Catalyst Particles by Nano‐XAFS

The Contribution of Synchrotron X-Ray Powder Diffraction to Modern Zeolite Applications: A Mini-review and Prospects

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New XAFS beamline for structural and electronic dynamics of nanoparticle catalysts in fuel cells under operating conditions

Cited by 28 publications

References 3 publications

Kinetics and Mechanism of Redox Processes of Pt/C and Pt3Co/C Cathode Electrocatalysts in a Polymer Electrolyte Fuel Cell during an Accelerated Durability Test

Kinetics and Mechanism of Redox Processes of Pt/C and Pt3Co/C Cathode Electrocatalysts in a Polymer Electrolyte Fuel Cell during an Accelerated Durability Test

Visualization of the Heterogeneity of Cerium Oxidation States in Single Pt/Ce2Zr2Ox Catalyst Particles by Nano‐XAFS

The Contribution of Synchrotron X-Ray Powder Diffraction to Modern Zeolite Applications: A Mini-review and Prospects

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Kinetics and Mechanism of Redox Processes of Pt/C and Pt₃Co/C Cathode Electrocatalysts in a Polymer Electrolyte Fuel Cell during an Accelerated Durability Test

Kinetics and Mechanism of Redox Processes of Pt/C and Pt₃Co/C Cathode Electrocatalysts in a Polymer Electrolyte Fuel Cell during an Accelerated Durability Test

Visualization of the Heterogeneity of Cerium Oxidation States in Single Pt/Ce₂Zr₂O_x Catalyst Particles by Nano‐XAFS