Effect of CeH2.73-CeO2 Composites on the Desorption Properties of Mg2NiH4

Wu, Kaiyao; Cai, Daqian; Shao, Kaimei; Xue, Tuguang; Zhang, Peng; Li, Wei; Lin, Huaijun

doi:10.3389/fchem.2020.00293

Cited by 10 publications

(2 citation statements)

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“…After discussing the hydride growth center and the overlayered hydrogen-incorporated layer we turn to the mutual effect of the two constituents. In terms of catalytic properties, the accessibility of hydrogens was shown to significantly affect the catalytic performance of hydrides. − Can we exploit the unique spectroscopic signature of hydrogen incorporation into the overlayer oxide as a probe to processes that occur underneath it?…”

Section: Resultsmentioning

confidence: 99%

“…Hence, the essential existence of a hydrogen reservoir in the vicinity of the active site encouraged efforts of exploring “symbiotic CeH 2+ x /CeO 2 catalysts” by combining ab initio calculations and electron microscopy. The benefit of using those structures in enhancing the catalytic activity was demonstrated for magnesium-based hydrides; , hydrogen released at the interface between cerium hydride and oxide plays an efficient catalytic role in enhancing the hydrogen desorption properties of Mg 2 NiH 4 .…”

Section: Introductionmentioning

confidence: 99%

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Raman Scattering from Cerium Hydride Growth Centers Overlayered by Hydrogen-Incorporated Oxide

Livneh¹,

Avisar²

2020

J. Phys. Chem. C

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A major driving force to the study of the interaction between H 2 and cerium oxides lies in elucidating their catalytic properties. Those can be modified by the accessibility of the hydrogen reservoir in the vicinity of the active site, which is potentially achieved by the presence of cerium hydrides within what has been recently referred to as "symbiotic CeH 2+x /CeO 2 catalysts". In this work, hydrogen exposure of cerium metal surfaces, covered by a thin native oxide overlayer, results in hydrogen incorporation within the oxide and the development of hydride growth centers underneath it. Partially reacted surfaces were investigated by Raman scattering spectroscopy and X-ray diffraction. The emergence of an ∼1005 cm −1 Ce−H local vibrational mode is revealed, while proposedly forming a CeO 2−x H y oxyhydride layer on top of the CeH ∼2 hydrides that form the growth centers. The local vibrational mode attribution is substantiated by the 2 isotopic effect of the band frequency when, instead of H 2 , the metal was reacted with D 2 . Monitoring the spatial dependence of its Raman intensity across growth centers with different radii provides a spectroscopic indicator to the pulverization of their brittle hydride interior, as it accompanies the concurrent rupture of the thin overlayer. The average hydride density, which is associated with the extent of pulverization, is extracted by estimating the volume of isolated growth centers, with radii of 65−450 μm. An estimated average packing density, for a large growth center with a radius of ∼450 μm, reached ∼50% relative to that of the bulk CeH 2 .

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