Hydride formation in palladium nanoparticles was studied by Pd K-edge X-ray absorption spectroscopy in both the near-edge (XANES) and the extended (EXAFS) regions and by X-ray diffraction (XRD) both in situ as a function of temperature and hydrogen pressure. In contrast to EXAFS and XRD, which probe Pd-Pd interatomic distance changes, the direct effect of hydrogen concentration on the electronic palladium structure is observed in the intensities and the peak positions in the XANES region. By using theoretical simulations, we propose a simple analysis of hydrogen concentration based on the changes of relative peak amplitudes in the XANES region, which correlate with interatomic distance changes determined by both EXAFS and XRD. By the quantitative analysis of XANES difference spectra, we have developed a scheme to determine the hydrogen concentration in palladium nanoparticles without applying any additional calibration procedures with alternative experimental techniques.

Temperature- and Pressure-Dependent Hydrogen Concentration in Supported PdHx Nanoparticles by Pd K-Edge X-ray Absorption Spectroscopy

BUGAEV, ARAM;LOMACHENKO, KIRILL;LAMBERTI, Carlo;
2014-01-01

Abstract

Hydride formation in palladium nanoparticles was studied by Pd K-edge X-ray absorption spectroscopy in both the near-edge (XANES) and the extended (EXAFS) regions and by X-ray diffraction (XRD) both in situ as a function of temperature and hydrogen pressure. In contrast to EXAFS and XRD, which probe Pd-Pd interatomic distance changes, the direct effect of hydrogen concentration on the electronic palladium structure is observed in the intensities and the peak positions in the XANES region. By using theoretical simulations, we propose a simple analysis of hydrogen concentration based on the changes of relative peak amplitudes in the XANES region, which correlate with interatomic distance changes determined by both EXAFS and XRD. By the quantitative analysis of XANES difference spectra, we have developed a scheme to determine the hydrogen concentration in palladium nanoparticles without applying any additional calibration procedures with alternative experimental techniques.
2014
118
19
10416
10423
http://pubs.acs.org/doi/abs/10.1021/jp500734p
METAL NANOPARTICLES; PALLADIUM NANOPARTICLES; IN-SITU; PARTICLE-SIZE; Palladium hydrate; EXAFS spectroscopy; XANES spectroscopy; X-ray powder diffraction; Ambrosia artemisiifolia; hydrogen absorption isotherm; Phase transformation; Alpha phase; Beta phase; XANES spectra simulation
A. L. Bugaev;A. A. Guda;K. A. Lomachenko;V. V. Srabionyan;L. A. Bugaev;A. V. Soldatov;C. Lamberti;V. P. Dmitriev;J. A. van Bokhoven
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/151943
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