Hydrogen desorption properties of magnesium hydride catalyzed multiply with carbon and silicon

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.