Hydrogen storage properties of nanostructured MgH sub(2/TiH) sub(2) composite prepared by ball milling under high hydrogen pressure

• Published in: International journal of hydrogen energy Vol. 36; no. 17; pp. 10828 - 10833
• Main Authors: Shao, H, Felderhoff, M, Schueth, F
• Format: Journal Article
• Language: English
• Published: 01-08-2011
• Subjects: Ball milling; Catalysts; Desorption; Entropy; Hydrogen storage; Mathematical analysis; Nanocomposites; Nanostructure
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2011.05.180

Nanostructured MgH sub(2/0.1TiH) sub(2) composite was synthesized directly from Mg and Ti metal by ball milling under an initial hydrogen pressure of 30 MPa. The synthesized composite shows interesting hydrogen storage properties. The desorption temperature is more than 100 degree C lower compared to commercial MgH sub(2 from TG-DSC measurements. After desorption, the composite sample absorbs hydrogen at 100 degree C to a capacity of 4 mass% in 4 h and may even absorb hydrogen at 40 degree C. The improved properties are due to the catalyst and nanostructure introduced during high pressure ball milling. From the PCI results at 269, 280, 289 and 301 degree C, the enthalpy change and entropy change during the desorption can be determined according to the van't Hoff equation. The values for the MgH) sub(2)/0.1TiH sub(2 nano-composite system are 77.4 kJ mol) super(-)1 H sub(2 and 137.5 J K) super(-)1 mol super(-1 H) sub(2), respectively. These values are in agreement with those obtained for a commercial MgH sub(2 system measured under the same conditions. Nanostructure and catalyst may greatly improve the kinetics, but do not change the thermodynamics of the materials.)