Facile synthesis of nickel-vanadium bimetallic oxide and its catalytic effects on the hydrogen storage properties of magnesium hydride

Abstract

To improve the dehydrogenation/hydrogenation performance of magnesium hydride (MgH2), a nickel-vanadium bimetallic oxide (NiV2O6) was prepared by a simple hydrothermal method using ammonium metavanadate and nickel nitrate as raw materials. This oxide was used to improve the hydrogen storage performance of MgH2. NiV2O6 reacted with Mg to form Mg2Ni and V2O5; Mg2Ni and V2O5 played an important role in improving the hydrogen storage properties of MgH2. The NiV2O6-doped MgH2 had an excellent hydrogen absorption and desorption kinetics performance, and it could absorb 5.59 wt% of hydrogen within 50 min at 150 °C and release about 5.3 wt% of hydrogen within 12 min. The apparent activation energies for the dehydrogenation and hydrogenation of MgH2-NiV2O6 were 92.9 kJ mol−1 and 24.9 kJ mol−1, respectively. These were 21.7% and 66.3% lower than those of MgH2, respectively. The mechanism analysis demonstrated that the improved kinetic properties of MgH2 resulted from the heterogeneous catalysis of vanadium and nickel.