Hydrogen desorption characteristics of Mg hydride films with Ni and Ni-based alloy catalyst layers deposited by magnetron sputtering

Abstract

We investigated the effects of nickel and nickel-based alloys as catalysts to reduce the hydrogen desorption temperatures of magnesium hydride films deposited by magnetron sputtering. We measured the hydrogen desorption spectra of magnesium hydride films with nickel and Ni-Co, Ni-Fe, Ni-Ti, and Ni-Cu alloy catalytic layers by thermal desorption spectroscopy. The chemical composition of the magnesium hydride films was MgH1.7 as determined by elastic recoil detection analysis and X-ray diffraction. MgH1.7 film with a nickel layer (Ni/MgH1.7) showed onset and termination temperatures of hydrogen desorption were 100°C and 178°C, respectively. The onset temperatures of Ni-Co/MgH1.7, Ni-Fe/MgH1.7, and Ni-Ti/MgH1.7 were higher than that of Ni/MgH1.7, which was almost the same as that of Ni-Cu/MgH1.7. To lower the hydrogen desorption temperature, we prepared a multilayer film [Ni/MgH1.7]5 by depositing MgH1.7 and nickel layers alternately five times, but this did not decrease the onset temperature of the multilayer film. On the basis of the experimental results, we discussed a possible mechanism underlying hydrogen desorption from magnesium hydride films with catalytic layers.