Synergistic Effect of a Facilely Synthesized MnVO Catalyst on Improving the Low-Temperature Kinetic Properties of MgH

While magnesium hydride (MgH) 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 MgH can be significantly improved using bimetallic oxide MnVO as the catalyst. A MgH-MnVO composite was prepared by a high-energy ball milling method. The results showed that the MgH-MnVO composite can release 5.57 wt % hydrogen within 10 min under 250 °C. The dehydrogenated MgH-MnVO 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 VO 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 MgH.