Catalytic mechanism of Nb2O5 and Ni on hydrogen storage properties of CeMg12-type alloy for automatic weather station emergency fuel cell

Abstract

In this paper, CeMg₁₂/Ni/Nb₂O₅ was prepared by mechanical ball milling technology for the sake of probing into the impact of Ni and Nb₂O₅ on microstructure and hydrogen sorption properties of alloys. The microstructure research results indicate that adding Nb₂O₅ can promote the formation of nanocrystal structure; through ball milling the Nb₂O₅ dispersed on the surface of alloy particles uniformly enhances the surface activity of the alloy and improves the hydrogen absorption and releasing kinetics of the alloy. The research on hydrogen absorption performance shows that the addition of Nb₂O₅ can significantly increase the hydrogen release platform pressure of the alloy hydride, the enthalpy value of hydrogen releasing process drops from 74.82 kJ/mol to 71.07 kJ/mol when the content of Nb₂O₅ is increased from 0 wt% to 9 wt%, the above qualitative and quantitative discussion further proves that Nb₂O₅ is beneficial for amending the thermodynamic stability of alloy hydride. Besides, adding Nb₂O₅ can remarkably reduce the hydrogen dissociation activation energy of experimental alloy hydride, ameliorating the dynamic performances of hydrogen release. The alloy with 9 wt% Nb₂O₅ has the smallest activation energy and the best performances of hydrogen release.