Stability of Catalyzed Magnesium Hydride Nanocrystalline During Hydrogen Cycling. Part II: Microstructure Evolution

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• 作者：Chengshang Zhou ; Zhigang Zak Fang ; Robert C. Bowman ; Jr. ; Yang Xia ; Jun Lu ; Xiangyi Luo ; Yang Ren
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：October 1, 2015
• 年：2015
• 卷：119
• 期：39
• 页码：22272-22280
• 全文大小：648K
• ISSN：1932-7455

文摘

In Part I, the cyclic stabilities of the kinetics of catalyzed MgH₂ systems including MgH₂鈥揟iH₂, MgH₂鈥揟iMn₂, and MgH₂鈥揤TiCr were investigated, showing stable kinetics at 300 掳C but deteriorations of the hydrogenation kinetics at temperatures below 150 掳C. The present Part II describes the characterization of uncycled and cycled catalyzed MgH₂ by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analysis. XRD analysis shows the crystallite sizes of the Mg and MgH₂ significantly increased after the cycling. The mean crystallite sizes of the catalysts (TiH₂ and VTiCr) increased moderately after the cycling. SEM and TEM imaging were used to compare the microstructures of uncycled (as-milled) and cycled materials, revealing a drastic change of the microstructure after 100 cycles. In particular, results from energy-dispersive spectroscopy (EDS) mapping show that a change of distribution of the catalyst particles in the Mg and MgH₂ phase occurred during the cycling.