Interaction of magnesium hydride clusters with Nb doped MgO additive studied by density functional calculations
A combined study of density functional theory calculations and experiments was performed to understand the role of Nb dissolved magnesium oxide (MgO) surfaces in improving the hydrogen storage performance of magnesium hydride (MgH2). Differential scanning calorimetry (DSC) studies confirm that MgH2 releases hydrogen at comparatively lower temperatures when MgO additive is replaced by Nb dissolved MgO. In order to verify this theoretically, two additive clusters, Mg4O4 and Mg3NbO4 were modeled by density functional theory technique and their interaction with H2 and MgH2 was investigated. The analysis confirms that the most favorable interaction, in terms of minimum energy structures, binding behavior and hydrogenation, can be achieved by the Mg3NbO4 additive. Interaction between Nb dissolved MgO cluster and MgH2 cluster is explained with the support of the highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO)/singly occupied molecular orbital (SOMO) surfaces and the related aspects of catalysis is discussed.