Magnetron sputtering as a method for introducing catalytic elements to magnesium hydride

Abstract

Magnesium hydride is a very interesting material suggested to be used for storing hydrogen because of its high capacity (∼7.5 wt%). However its application is limited by high decomposition temperature and poor kinetics. This paper presents results of the preliminary study on the new approach to introduction of surface dopants by magnetron sputtering on powdery substrates. Thin films of nickel were successfully deposited on the magnesium hydride powder. SEM observations and EDS elements mapping show uniform and continuous layers, with the thickness up to 320 nm, formed on hydride grains. It was proven by measurements with Sievert's method that such a surface modification increases the H2 dissociation/recombination speed and effectively enhances hydrogenation/dehydrogenation reaction rate. The DSC measurements show the reduction of the activation energy of hydrogen desorption by ∼150 kJ/mol and a decrease of the decomposition temperature by 50 K. The study shows that uniform nickel coating of hydride powder by magnetron sputtering can be considered as an effective way for introduction of the catalytic elements and improvement of the hydrogen storage properties of the magnesium hydride.