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In-situ TEM Observation for Reaction Mechanism in MgH2 Hydrogen Storage Material

Published online by Cambridge University Press:  31 January 2011

Akifumi Ono
Affiliation:
Shigehito Isobe
Affiliation:
[email protected], Hokkaido University, Sapporo, Japan
Yongming Wang
Affiliation:
[email protected], Hokkaido University, Sapporo, Japan
Naoyuki Hashimoto
Affiliation:
[email protected], Hokkaido University, Sapporo, Japan
Somei Ohnuki
Affiliation:
[email protected], Hokkaido University, Sapporo, Japan
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Abstract

In-situ observation on the catalytic effect of Nb2O5 in MgH2 was carried out by using transmission electron microscopy (TEM). We prepared two kinds of samples, because we tried to observe the reaction from two kinds of viewpoints. MgH2 catalyzed with 1 mol% of Nb2O5 was prepared for an overall viewpoint on the desorption process of MgH2 with catalyst by conventional TEM. The dehydrogenation of the 1 mol% sample started at 150 °C and Mg nano-size particles were formed. However, Nb2O5 was not confirmed in diffraction patterns and images, because it was highly dispersed by ball-milled. So MgH2 catalyzed with 10 mol% of Nb2O5 was prepared for local viewpoint to focus the boundary between the catalyst and the Mg phase by high voltage electron micro scope (HVEM). The sample mixed in mortar was prepared for this, because it was difficult to find the boundary in the sample ball-milled. The high resolution images of the 10 mol% sample revealed that the dehydrogenation started from the interface of MgH2 and Nb2O5. The result suggested that the dehydrogenation could proceed with hydrogen diffusion from MgH2 phase to the interface between Mg and Nb2O5.

Type
Research Article
Copyright
Copyright © Materials Research Society 2010

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