Reversible hydrogen storage behaviors and microstructure of TiC-doped sodium aluminum hydride
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TiC-doped NaAlH4 complex hydride was prepared by hydrogenating of ball-milled NaH/Al mixture in the presence of 5 mol% TiC powder, and its hydrogen storage behaviors and microstructure were investigated. It is found that TiC is a good catalyst for the reversible hydriding/dehydriding process of NaAlH4 at moderate temperatures by reducing the decomposition temperature and improving the hydriding/dehydriding kinetics. The hydrogen desorption capacity of 5 mol% TiC-doped NaAlH4 is 4.6 wt% at 165 °C and its average dehydriding rate in the first 30 min reaches 0.107 wt%/min. X-ray diffraction analyses show that the size of crystal grains of the composites is reduced by ball-milling, and is then increased rapidly in the first hydriding–dehydriding cycle. Scanning electron micrographs represent that the particle size of the ball-milled composites is quite even and averages around 50 nm. However, it changes into a widely distributed one ranging from 50 nm to 1 μm in the subsequent hydriding–dehydriding cycles. DSC measurement indicates that the doping of TiC can lower the dehydriding temperatures of sodium aluminum hydride.
KeywordsDehydrogenation Hydrogen Storage Hydrogen Storage Capacity Hydrogen Capacity NaAlH4
This work is jointly supported by the National Basic Research Program of China (2007CB209701), the National Natural Science Foundation of China (50871099, 50631020), the Program for New Century Excellent Talents in Universities (NCET-07-0741), and the China Postdoctoral Science Foundation (20080440196).
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