Characterization of amorphous Nb oxide and its influence on Mg hydrogen sorption

Abstract

Abstract Amorphous Nb2O5 was synthesized by combining niobium ethoxide with an amine surfactant. The material turned out to have a high surface area, 287 m2 g−1, and a homogeneous structure. The material was shown to be amorphous despite the heat treatment performed within a range of 150 to 550°C. The surface area of Nb2O5 reduced to 105 m2 g−1 after heat treating at 350°C. The activation energy of the Nb2O5 crystallization reaction was found to be 327 kJ mol−1. The surface area of Nb2O5 reduced significantly with heat treatment but it still improved the hydrogen kinetics since the desorption rate was 1.5 wt.% min−1. The addition of a small amount of amorphous Nb2O5 to magnesium hydride, throughout milling, helped overcoming limitations inherent to solid hydrogen storage.