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

Journal Article · Thu Oct 01 04:00:00 EDT 2015 · Journal of Physical Chemistry. C

DOI:https://doi.org/10.1021/acs.jpcc.5b06192· OSTI ID:1390927

Zhou, Chengshang; Fang, Zhigang Zak; Bowman, Robert C.; Xia, Yang; Lu, Jun; Luo, Xiangyi; Ren, Yang

In Part I, the cyclic stabilities of the kinetics of catalyzed MgH2 systems including MgH2–TiH2, MgH2–TiMn2, and MgH2–VTiCr were investigated, showing stable kinetics at 300 °C but deteriorations of the hydrogenation kinetics at temperatures below 150 °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.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1390927
• Journal Information: Journal of Physical Chemistry. C, Journal Name: Journal of Physical Chemistry. C Journal Issue: 39 Vol. 119; ISSN 1932-7447
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English