Synergistic Effect of a Facilely Synthesized MnV₂O₆ Catalyst on Improving the Low-Temperature Kinetic Properties of MgH₂

Abstract

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.

Short-Range Nanoreaction Effect on the Hydrogen Desorption Behaviors of the MgH2–Ni@C Composite

“…As shown in Figure 5a, even after 50 cycles of hydrogen absorption at 150 °C and desorption at 275 °C, the MgH 2 −5 wt % Ni@C composite exhibited excellent reversibility, and the total capacity decay for hydrogen absorption and desorption was only 2.9 and 5.6% after 50 cycles, respectively. Compared with other MgH 2 −catalyst composites, 15,43,56,57 the MgH 2 −5 wt % Ni@C composite in this work exhibits superior cycling stability. We observed the microstructure and phase composition of the MgH 2 −5 wt % Ni@C composite before and after hydrogen absorption/ desorption cycling.…”

Dual tuning of the de-/hydrogenation thermodynamics and kinetics of the Mg–Ni alloy by introducing the Ag–H bond: enhanced hydrogen storage properties at moderate temperatures

“…However, as the reaction conditions change, the corresponding reaction models will also change. [43][44][45] In order to investigate the rate-limiting step of isotherm dehydrogenation, the classical nucleation and growth model, Johnson-Mechl-Avrami (JMA) model, 2,23 is applied to t the experimental data. The equation of the JMA model is…”

Enhanced hydrogen storage kinetics of MgH2 by the synergistic effect of Mn3O4/ZrO2 nanoparticles

“…29–31 For example, Fu et al . 32 found that MnV 2 O 6 catalyzed MgH 2 could discharge 5.57 wt% hydrogen at 250 °C and charge 3.09 wt% hydrogen at 50 °C in 10 min. Lu et al .…”

“…Numerous previous studies have shown that the synergistic impact between different elements or phases can further increase the catalytic activity and improve MgH 2 properties. [29][30][31] For example, Fu et al 32 found that MnV 2 O 6 catalyzed MgH 2 could discharge 5.57 wt% hydrogen at 250 °C and charge 3.09 wt% hydrogen at 50 °C in 10 min. Lu et al 33 proved that MgH 2 + ZrO 2 @Nb 2 CTx could release 6.24 wt% hydrogen at 300 °C in 150 s and about 5.69 wt% hydrogen was discharged in 15 min even at 240 °C.…”