Graphene-loaded nickel-vanadium bimetal oxides as hydrogen pumps to boost solid-state hydrogen storage kinetic performance of magnesium hydride
To modify the thermodynamics and kinetic performance of magnesium hydride(MgH2)for solid-state hydrogen storage,Ni3V2O8-rGO(rGOrepresents reduced graphene oxide)and Ni3V2O8 nanocomposites were prepared by hydrothermal and subsequent heat treatment.The beginning hydrogen desorption temperature of 7 wt.％Ni3V2O8-rGO modified MgH2 was reduced to 208 ℃,while the additive-free MgH2 and 7 wt.％Ni3V2O8 doped MgH2 appeared to discharge hydrogen at 340 and 226 ℃,respectively.A charging capacity of about 4.7 wt.％H2 for MgH2+7 wt.％Ni3V2O8-rGO was achieved at 125 ℃ in 10 min,while the dehydrogenated MgH2 took 60 min to absorb only 4.6 wt.％H2 at 215 ℃.The microstructure analysis confirmed that the in-situ generated Mg2Ni/Mg2NiH4 and metallic V contributed significantly to the enhanced performance of MgH2.In addition,the presence of rGO in the MgH2+7 wt.％Ni3V2O8-rGO composite reduced particle aggregation tendency of Mg/MgH2,leading to improvingthe cyclic stability of MgH2during 20 cycles.
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