Effect of LaFeO_3 on hydrogenation/dehydrogenation properties of MgH_2

LaFeO3 was used to improve the hydrogen storage properties of Mg H2. The Mg H2＋20 wt.%La Fe O3 composite was prepared by ball milling method. The composite could absorb 3.417 wt.% of hydrogen within 21 min at 423 K while Mg H2 only uptaked 0.977 wt.% hydrogen under the same conditions. The composite also released 3.894 wt.% of hydrogen at 623 K, which was almost twice more than Mg H2. The TPD measurement showed that the onset dissociation temperature of the composite was 570 K, 80 K lower than the Mg H2. Based on the Kissinger plot analysis of the composite, the activation energy E des was estimated to be 86.69 k J/mol, which was 36 k J/mol lower than Mg H2. The XRD and SEM results demonstrated that highly dispersed La Fe O3 could be presented in Mg H2, benefiting the reduction of particle size and also acting as an inhibitor to keep the particles from clustering during the ball-milled process.