Abstract Magnesium hydride (MgH2) is considered as one of hydrogen storage materials. However, the application is limited because of slow hydrogen kinetics and high thermodynamic stability. In this study, MgH2 powders were mechanically milled with graphite (C) and/or silicon (Si) powders, and effect of multiple addition of C and Si on hydrogen desorption properties was investigated. The multiple addition caused a decrease of the hydrogen desorption (onset and peak) temperatures more than single addition, and the lowest activation energy for hydrogen desorption, 62 kJ/mol, was obtained from sample powders of (2 mol MgH2 + 0.5 mol C + 0.5 mol Si). The surface of the sample powders after mechanical milling revealed a good distribution of C on the MgH2 surface and a presence of finer Si particles.
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