While magnesium hydride (MgH2) has drawn considerable attention as a promising hydrogen storage material, it suffers from sluggish kinetics and high desorption temperature, hindering potential applications. Herein, we show that the hydrogen desorption kinetics of MgH2 can be significantly improved using bimetallic oxide MnV2O6 as the catalyst. A MgH2-MnV2O6 composite was prepared by a high-energy ball milling method. The results showed that the MgH2-MnV2O6 composite can release 5.57 wt % hydrogen within 10 min under 250 °C. The dehydrogenated MgH2-MnV2O6 sample can absorb 3.09 wt % hydrogen within 10 min under 50 °C. Notably, the reversible hydrogen storage property did not degrade at least within 100 cycles, showing excellent cycle stability. X-ray diffraction and transmittance electron microscopy measurements revealed that MnV alloy and V2O3 phases were formed during the ball milling process, leading to the synergistic catalytic effect. We argue that the bimetallic MnV alloy plays key catalytic roles in this system because MnV alloy can promote the fracture of the H-H and Mg-H bonds, significantly improving the hydrogen storage kinetics and low-temperature reversible hydrogen storage performance of MgH2.
Keywords: MnV alloy; bimetallic oxides; hydrogen storage; magnesium hydride; synergistic effect.