PreparationandhydrogenstoragepropertiesofMgH2-trimesicacid-TMMOF（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 Mg H2-TM MOF（TM = Co, Fe） composites via ball-milling. X-ray diffraction analyses show the formation of Mg2 Co and α-Fe phases in Mg H2-TMMOF composites after decomposition. Both of the well dispersed Mg2Co andα-Fe nanoparticles exhibit considerable catalytic efficiency in accelerating the sorption kinetics of Mg H2.The dehydrogenated MgH2-Fe MOF composite shows faster hydriding kinetics than the pure Mg H2 and Mg H2-CoMOF. Meanwhile, the apparent dehydrogenation activation energy（Ed） of the Mg H2-Co MOF and Mg H2-Fe MOF composites are 151.3 ± 9.4 and 142.3 ± 6.5 kJ/mol H2, both of which are lower than that of pure Mg H2（181.4 ± 9.2 kJ/mol H2）. The improvement on the sorption kinetics of the Mg H2-TM MOF powders is mainly attributed to the catalytic effects of nano-sized Mg2 Co and α-Fe formed on the surface of Mg/Mg H2 particles.