Hydrogen storage of intrinsic and vanadium-decorated Mg nanostructures

MgH$_{2}$ is very attractive for future solid state H-storage applications, due to its lightweight, low cost, and high H-storage capacity of 7.6 wt{\%}. However, its practical application is limited by its high thermodynamic stability and sluggish reaction kinetics, which could be improved by making nanostructures with large surface-to-volume ratios to enhance surface reaction activity and by adding an appropriate catalyst to accelerate H-sorption kinetics. In this work, an oblique angle deposition (OAD) or oblique angle co-deposition (OACD) technique has been used to sculpture Mg nanostructures and incorporate a nanocatalyst. For an intrinsic Mg film and Mg nanoblade array by OAD on Ti coated Si, the hydrogenation results show that the nanoblades start to absorb H$_{2}$ at 523 K$$ 500 K after activation by one hydrogenation cycling, with low H-absorption activation energy of 35.0 $\pm $ 1.2 kJ/mol H$_{2}$ and desorption activation energy of 65.0 $\pm $ 0.3 kJ/mol H$_{2}$. The improved H-sorption kinetics is attributed to both the catalytic effect of the V coating and the unique nanoblade morphology.