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

Highlights: • The 1-D Niobate W and Niobate C catalysts were synthesized. • The composites MgH₂ + 5 wt.% catalysts were obtained by 20 min of mechanical milling. • The synthesized wired-like material 1-D Niobate W showed to be a promising catalyst. • A desorption capacity of 6.0 wt.%. of H₂ was attained in 10 min with MgH₂ + 5 wt.% 1-D Niobate W. - 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 10 M 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 20 min 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 + 5 wt.% 1-D Niobate W composite, reaching, in 10 min, approximately 5.0 wt.% and 6.0 wt.%, respectively. The possible mechanism involved in such property improvement upon adding niobium based catalysts with different morphology and structure was discussed