Abstract
BACKGROUND: Magnesium hydride is considered to be a promising hydrogen storage material because of its high gravimetric and volumetric storage capacities. However, its slow kinetics and high desorption temperature of > 300 °C limit practical applications. In this work, TiC nanoparticles were selected to modify the hydrogen storage properties of MgH~2~. Composite mixtures (MgH~2~ + TiC) were prepared using both cryogenic milling and high‐energy ball milling.
RESULTS: The resulting morphology and crystallite structure of the composites were identified by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X‐ray diffraction (XRD). The milled samples show good mixing of the hydride and carbide particles, with MgH~2~ particles around 0.09–1 µm and TiC particles 10–20 nm. The (MgH~2~ + TiC) composites consist of γ‐MgH~2~, β‐MgH~2~ and TiC. MgH~2~ nano‐crystallites of 25 nm were formed after cryomilling. Thermogravimetry reveals that the composites release ∼6.5 mass % hydrogen from 190–400 °C at a heating rate of 10 °C min^−1^ under He flow, with the onset and peak temperatures at 190 and 280 °C, respectively, for the (MgH~2~ + TiC) after 8 h cryomilling and 60 h ball milling.
CONCLUSION: Results indicate that TiC is an effective catalyst for hydrogen desorption of MgH~2~. Copyright © 2010 Society of Chemical Industry