The use of one-dimensional Niobate to improve MgH2 hydrogen sorption

Abstract

A study was performed on the hydrogen absorption/desorption properties of MgH2 with the addition of Niobates synthesized by hydrothermal treatment of Nb2O5 in 10M NaOH. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) were used to evaluate their synthesis and show the morphological and crystallographic differences between Nb2O5 used as a precursor and the Niobates produced, the one-dimensional wired type, 1-D Niobate W and the cuboid one, Niobate C. The ball milling of MgH2 with the Niobates was performed within only 20min and afterwards the Differential Scanning Calorimetry (DSC) examination of MgH2+1-D Niobate W and MgH2+Niobate C showed the shifting of the peaks for both composites in comparison to pure MgH2. The influence of the two different types of Niobates and also the Nb2O5 on the hydrogen absorption/desorption capacity was evaluated at 350°C. The higher absorption and desorption values were attained by the MgH2+5wt.% 1-D Niobate W composite, reaching, in 10min, approximately 5.0wt.% and 6.0wt.%, respectively. The possible mechanism involved in such property improvement upon adding niobium based catalysts with different morphology and structure was discussed.