Hydrogen storage properties of MgH2–Tm: Ni-catalysis vs. mechanical milling

Abstract

The influence of the addition of nickel on hydrogen desorption from the MgH2–Ni composite was investigated. The composite powder was ball-milled for 15, 30 and 45 min and characterized by XRD, SEM-EDS, PSD, DSC and TPD methods. It was observed that the uniform distribution of nickel decreases hydrogen desorption temperature by more than 100 °C. A kinetic model for the hydrogen desorption process was also determined. The hydrogen desorption reaction in catalyzed samples is described by the Avrami-Erofeev model with the value of parameter n = 4. The apparent activation energy of the hydrogen desorption reaction was decreased with the increase of milling time and the addition of nickel. It has been shown for the first time that two main processes (grinding and the catalytic effect) could be separately analyzed. It is concluded that for investigated short milling times, the catalytic effect of Ni is predominant.