Enhancing Hydrogen Storage Properties of MgH₂ by Transition Metals and Carbon Materials: A Brief Review

Magnesium hydride (MgH₂) has attracted intense attention worldwide as solid state hydrogen storage materials due to its advantages of high hydrogen capacity, good reversibility, and low cost. However, high thermodynamic stability and slow kinetics of MgH₂ has limited its practical application. We reviewed the recent development in improving the sorption kinetics of MgH₂ and discovered that transition metals and their alloys have been extensively researched to enhance the de/hydrogenation performance of MgH₂. In addition, to maintain the cycling property during the de/hydrogenation process, carbon materials (graphene, carbon nanotubes, and other materials) have been proved to possess excellent effect. In this work, we introduce various categories of transition metals and their alloys to MgH₂, focusing on their catalytic effect on improving the hydrogen de/absorption performance of MgH₂. Besides, carbon materials together with transition metals and their alloys are also summarized in this study, which show better hydrogen storage performance. Finally, the existing problems and challenges of MgH₂ as practical hydrogen storage materials are analyzed and possible solutions are also proposed.