Improved reversible dehydrogenation performance of MgH2 by the synergistic effects of porous boron nitride and NbF5

Abstract

In this work, porous boron nitride (pBN) and NbF5 were used to improve the hydrogen storage performance of magnesium hydride (MgH2), especially the reversibility and dehydrogenation kinetics. We also carried out a series of control experiments to optimize the sample preparation method and addition amount of pBN. Comparing with the pristine MgH2 system, the as-prepared MgH2/NbF5@pBN sample exhibits promoting dehydrogenation kinetics. And it rapidly began to release hydrogen from around 230 °C, which was 140 °C lower. Moreover, it took 10 min during all the dehydrogenation process. A series of phase and chemical state analyses was used to study the enhanced effects of NbF5@pBN on the reversible hydrogen storage performance of MgH2. And the study demonstrates pBN is an effective additive as confinement medium and catalysis of the surface dangling-bond for improving the reversible dehydrogenation of MgH2. NbF5 could also act as catalysts. Therefore, the prominently improved dehydrogenation performance of MgH2 should be ascribed to a synergistic effect of nanoconfinement and catalysis.