MOF-derived carbon supported transition metal (Fe, Ni) and synergetic catalysis for hydrogen storage kinetics of MgH2

Abstract

The synthesis of trimesic acid-Ni/Fe based metal organic frameworks (TAM-Fe MOF and TAM-Ni MOF) at room temperature, followed by doping their derivatives into MgH2 system via mechanical ball milling, has shown promising results in enhancing hydrogen storage performance. Both monometallic and bimetallic catalysts loaded with carbon have promoted the kinetics of the MgH2/Mg system, with the latter exhibiting superior catalytic performance. The composite MgH2 + 10 wt% TM/C (TM = Fe, Ni) demonstrates an initial hydrogen desorption temperature of 194 °C and rapid absorption of 6.2 wt% H2 within 60 s at 150 °C, along with absorbing 5.7 wt% H2 within 1 h at 100 °C. Complete hydrogen desorption occurs at 300 °C, with an activation energy (Eα) for hydrogen desorption process is 77.3 kJ mol−1. Mechanistic studies reveal that in-situ generated Fe, Mg2Ni, and Mg2NiH4 are the actual catalytic active substances, exhibiting synergistic effects and providing more active sites, with Mg2Ni/Mg2NiH4 acting as a “hydrogen pump”. Additionally, the carbon loaded transition metal particles facilitate hydrogen diffusion and inhibit the aggregation of MgH2/Mg particles, making this approach cost-effective and viable for hydrogen storage catalysis applications.