Enhancing hydrogen storage properties of MgH2 through addition of Ni/CoMoO4 nanorods

In this work, one-dimensional NiMoO 4 and CoMoO 4 nanorods are prepared and introduced into MgH 2 to improve its hydrogen storage properties. It is observed that the MgH 2 –NiMoO 4 system exhibits lower dehydrogenation temperature and faster kinetics than the MgH 2 –CoMoO 4 system and pure MgH 2 , indicating the superior promoting effect of NiMoO 4 over CoMoO 4 . Concretely, NiMoO 4 reacts with MgH 2 during the first dehydrogenation to in situ form Mg 2 Ni and Mo 0 , both of which are crucial factors for the following hydrogen cycling process. The ‘Mg 2 Ni/Mg 2 NiH 4 ’ mutual transformation upon hydrogen release/uptake is the well-known ‘hydrogen pump’ effect which boosts the hydrogen storage performance of MgH 2 . Moreover, theoretical calculations reveal the dual roles of Mo 0 played for the hydrogen storage in MgH 2 : i) it accelerates the hydrogen de/absorption of MgH 2 through weakening the Mg–H bonding; ii) it facilitates the mutual ‘Mg 2 Ni/Mg 2 NiH 4 ’ transformation as the formation energy of Mg 2 NiH 4 decreases under the influence of Mo 0 , which we call ‘facilitated hydrogen pump’ effect in this work. Ascribing to the collaborative action between Ni- and Mo- containing species, the hydrogen storage kinetics of MgH 2 has been accelerated.