Investigation on hydrogenation performance of Mg2Ni+10 wt.% NbN composite

Abstract

The Mg2Ni+10wt.% NbN composite was prepared by mechanical milling and its hydrogen absorption/desorption properties and microstructure were systematically investigated. XRD results indicated that NbN was stable during ball milling process while partly decomposed into NbN0.95 and NbH during hydriding/dehydriding cycles irreversibly. The composite exhibited excellent hydrogenation/dehydrogenation kinetics performance with 2.71 wt.% hydrogen absorbed in 60s at 423K and 0.81 wt.% hydrogen released in 2h at 523K, respectively. The H diffusion constant of the composite reached 14.98×10−5s−1 which was more than twice increased than that of pure Mg2Ni powder. The superior hydrogen storage properties of the composite were ascribed to the refined grain size and abundant N-defect points provided by NbN and NbN0.95 in the composite.