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 MgH 2 -TM MOF (TM = Co, Fe) composites via ball-milling. X-ray diffraction analyses show the formation of Mg 2 Co and α-Fe phases in MgH 2 -TM MOF composites after decomposition. Both of the well dispersed Mg 2 Co and α-Fe nanoparticles exhibit considerable catalytic efficiency in accelerating the sorption kinetics of MgH 2 . The dehydrogenated MgH 2 -Fe MOF composite shows faster hydriding kinetics than the pure MgH 2 and MgH 2 -Co MOF. Meanwhile, the apparent dehydrogenation activation energy ( E d ) of the MgH 2 -Co MOF and MgH 2 -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 MgH 2 (181.4 ± 9.2 kJ/mol H 2 ). The improvement on the sorption kinetics of the MgH 2 -TM MOF powders is mainly attributed to the catalytic effects of nano-sized Mg 2 Co and α-Fe formed on the surface of Mg/MgH 2 particles.