Preparation and hydrogen storage properties of MgH2-trimesic acid-TM MOF (TM=Co, Fe) composites

Two kinds of metal-organic frameworks (MOFs) based on Co (II) and Fe (II) as metal ions and trimasic acid (TMA) as organic linker were synthesized. They were used to prepare corresponding MgH2-TM MOF (TM=Co, Fe) composites via ball-milling. X-ray diffraction analyses show the formation of Mg2Co and alpha-Fe phases in MgH2-TM MOF composites after decomposition. Both of the well dispersed Mg Co and alpha-Fe nanoparticles exhibit considerable catalytic efficiency in accelerating the sorption kinetics of MgH2. The dehydrogenated MgH2-Fe MOF composite shows faster hydriding kinetics than the pure MgH2 and MgH2-Co MOF. Meanwhile, the apparent dehydrogenation activation energy (E-d) of the MgH2-Co MOF and MgH2-Fe MOF composites are 151.3 +/- 9.4 and 142.3 +/- 6.5 kJ/mol H-2, both of which are lower than that of pure MgH2 (181.4 +/- 9.2 kJ/mol H-2). The improvement on the sorption kinetics of the MgH2-TM MOF powders is mainly attributed to the catalytic effects of nano-sized Mg2Co and alpha-Fe formed on the surface of Mg/MgH2 particles. (C) 2019 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.