Understanding the dehydrogenation properties of Mg(0001)/MgH2(110) interface from first principles

Abstract

Magnesium hydride is one of the most promising solid-state hydrogen storage materials for on-board application. Hydrogen desorption from MgH₂ is accompanied by the formation of the Mg/MgH₂ interfaces, which may play a key role in the further dehydrogenation process. In this work, first-principles calculations have been used to understand the dehydrogenation properties of the Mg(0001)/MgH₂(110) interface. It is found that the Mg(0001)/MgH₂(110) interface can weaken the Mg–H bond. The removal energies for hydrogen atoms in the interface zone are significantly lower compared to those of bulk MgH₂. In terms of H mobility, hydrogen diffusion within the interface as well as into the Mg matrix is considered. The calculated energy barriers reveal that the migration of hydrogen atoms in the interface zone is easier than that in the bulk MgH₂. Based on the hydrogen removal energies and diffusion barriers, we conclude that the formation of the Mg(0001)/MgH₂(110) interface facilitates the dehydrogenation process of magnesium hydride.