Catalytic effect of carbon nanostructures on the hydrogen storage properties of MgH2-NaAlH4 composite

The present investigation describes the hydrogen storage properties of 2:1 molar ratio of MgH2-NaAlH4 composite. De/rehydrogenation study reveals that MgH2-NaAlH4 composite offers beneficial hydrogen storage characteristics as compared to pristine NaAlH4 and MgH2. To investigate the effect of carbon nanostructures (CNS) on the de/rehydrogenation behavior of MgH2-NaAlH4 composite, we have employed 2 wt.% CNS namely, single wall carbon nanotubes (SWCNT) and graphene nano sheets (GNS). It is found that the hydrogen storage behavior of composite gets improved by the addition of 2 wt.% CNS. In particular, catalytic effect of GNS + SWCNT improves the hydrogen storage behavior and cyclability of the composite. De/rehydrogenation experiments performed up to six cycles show loss of 1.50 wt.% and 0.84 wt.% hydrogen capacity in MgH2-NaAlH4 catalyzed with 2 wt.% SWCNT and 2 wt.% GNS respectively. On the other hand, the loss of hydrogen capacity after six rehydrogenation cycles in GNS + SWCNT (1.5 + 0.5) wt.% catalyzed MgH2-NaAlH4 is diminished to 0.45 wt.%.