Effect of MOF-derived nanoparticle-cumulated flower-like CoFe@C coated composites on hydrogenation/dehydrogenation performance of MgH2

Magnesium hydride (MgH2) has garnered substantial consideration mainly due to its high gravimetric density and reliable resource, whereas its poor thermodynamics and kinetics for absorbing/releasing hydrogen restricts the largescale application. Certain catalysts have demonstrated remarkable activity in enhancing the hydrogen storage capabilities of MgH2. In this work, the nanoparticle-cumulated flower-like CoFe@C coated catalysts (denoted as CoFe@C) are controllably synthesized as expected by the MOF (Metal-Organic Farmwork) in-suit decomposition method at 800 °C, which exhibits an average pore size of 18.63 nm. Meanwhile, the particle size for the as-prepared CoFe alloy coated in carbon layer are approximately 10–20 nm, and the as-prepared samples are introduced to promote the de/rehydrogenation properties of MgH2 at relatively lower temperatures. Due to the synergistic interaction of CoFe alloy nanoparticles serving as active sites and agglomeration resistance of carbon layers, the MgH2 composites doped with CoFe@C-800 could initialize its decomposition process at 175.9 °C, and may desorb 6.0 wt% H2 at 300 °C in 400 s. Additionally, the peak temperature and apparent activation energy during dehydrogenation decline significantly (with 35 % and 38 %, respectively). Furthermore, theoretical analysis results indicate a higher catalytic activity for the carbon-coated CoFe alloy owing to the synergetic effect between CoFe nanocomposite & carbon layer, which can facilitate the bond extension and strength decrease of Mg-H bonding. In brief, using MOF may derive transition metal and carbon layer, which could be a promising approach to stimulating the hydrogen storage properties of MgH2.