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Experimental methods in chemical engineering: X ‐ray absorption spectroscopy— XAS , XANES , EXAFS

Ana Iglesias‐Juez, Gian Luca Chiarello, Gregory Patience, M. Olga Guerrero‐Pérez

Article (2021)

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Abstract

Although X-ray absorption spectroscopy (XAS) was conceived in the early 20th century, it took 60 years after the advent of synchrotrons for researchers to exploit its tremendous potential. Counterintuitively, researchers are now developing bench type polychromatic X-ray sources that are less brilliant to measure catalyst stability and work with toxic substances. XAS measures the absorption spectra of electrons that X-rays eject from the tightly bound core electrons to the continuum. The spectrum from 10 to 150 eV (kinetic energy of the photoelectrons) above the chemical potential—binding energy of core electrons—identifies oxidation state and band occupancy (X-ray absorption near edge structure, XANES), while higher energies in the spectrum relate to local atomic structure like coordination number and distance, Debye-Waller factor, and inner potential correction (extended X-ray absorption fine structure, EXAFS). Combining XAS with complementary spectroscopic techniques like Raman, Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) elucidates the nature of the chemical bonds at the catalyst surface to better understand reaction mechanisms and intermediates. Because synchrotrons continue to be the light source of choice for most researchers, the number of articles Web of Science indexes per year has grown from 1000 in 1991 to 1700 in 2020. Material scientists and physical chemists publish an order of magnitude articles more than chemical engineers. Based on a bibliometric analysis, the research comprises five clusters centred around: electronic and optical properties, oxidation and hydrogenation catalysis, complementary analytical techniques like FTIR, nanoparticles and electrocatalysis, and iron, metals, and complexes.

Uncontrolled Keywords

EXAFS, operando, synchrotron, XANES, XAS

Subjects: 1800 Chemical engineering > 1800 Chemical engineering
Department: Department of Chemical Engineering
Funders: Erasmus+ KA107, Universidad de Malaga/CBUA, Canada Research Chairs program
Grant number: 2018-1-ES01-KA107-049563, 950-231476
PolyPublie URL: https://publications.polymtl.ca/9247/
Journal Title: The Canadian Journal of Chemical Engineering
Publisher: Wiley
DOI: 10.1002/cjce.24291
Official URL: https://doi.org/10.1002/cjce.24291
Date Deposited: 20 Jan 2022 16:13
Last Modified: 11 Nov 2022 14:14
Cite in APA 7: Iglesias‐Juez, A., Chiarello, G. L., Patience, G., & Guerrero‐Pérez, M. O. (2021). Experimental methods in chemical engineering: X ‐ray absorption spectroscopy— XAS , XANES , EXAFS. The Canadian Journal of Chemical Engineering, 1-20. https://doi.org/10.1002/cjce.24291

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