Ball-milled graphite can absorb a relatively large amount of hydrogen (6.1 wt%) . However, the reversibility of hydrogenated graphite is very poor and desorption gases have been typically reported to contain methane, which has limited its development as a hydrogen storage medium. The prevention of hydrocarbon desorption is a prerequisite to the development of reversibility. The desorption of pure hydrogen could be achieved by carefully controlling the ball- milling duration3. However, hydrogen trapping sites, and the relationship between the microstructure and the reversibility of hydrogen storage, are not yet satisfactorily understood. There are two main views about hydrogen trapping positions in graphite: at the edge of graphite layers4-5; or in the space between adjacent graphite layers6. To try to understand hydrogen sorption in milled graphite, and so, ultimately, improve the reversibility of the carbon-hydrogen system, powder characteristics and hydrogen storage properties of graphite ball-milled in hydrogen have been investigated.
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