Effects of BaRuO3 addition on hydrogen desorption in MgH2

Hydrogen storage in MgH2 is strongly limited by kinetic constraints, so that several additives have been considered in order to improve the rate of hydrogen desorption. The present work is devoted to investigate the effect of BaRuO3 addition on hydrogen absorption and desorption properties of MgH2. BaRuO3 was prepared by solid-state synthesis of BaO and Ru in oxidizing environment. The interaction of as-prepared BaRuO3 with hydrogen at room temperature was examined by thermal desorption and X-ray diffraction experiments, showing that BaRuO3 has the ability to uptake hydrogen in the bulk. The hydrogen interaction is discussed with respect to octahedral ruthenium local environment present in the oxide structure. Addition of 1 mol.% BaRuO3 to MgH2 was performed by ball milling. Hydrogen desorption properties were investigated by Sievert and DSC, connected with a H-2 detector. The H-2 desorbed from of the nano-structured materials is lower than the theoretical content in MgH2, due to the presence of a non-reactive MgO layer. A remarkable increase of the H-2 desorption kinetics in nano-structured MgH2 was observed with respect to bare MgH2. The activation energy for hydrogen desorption from MgH2/BaRuO3 mixture was estimated by Arrhenius and Kissinger methods and a value around 130 kJ mol(-1) and 90 kJ mol(-1) was obtained, respectively. (c) 2011 Elsevier B.V. All rights reserved.