Hydrogen storage properties of Mg98.5Gd1Zn0.5 and Mg98.5Gd0.5Y0.5Zn0.5 alloys containing LPSO phases. (21st September 2021)

• Record Type: Journal Article
• Authors: He, J.H.; Zhang, J.; Zhou, X.J.; Chen, J.N.; Yu, L.P.; Jiang, L.K.; Lu, X.Z.; Chen, X.M.; Zhou, D.W.
• Is Part Of: International journal of hydrogen energy. Volume 46:Number 65(2021)
• Page Start: 32949
• Page End: 32961
• Publication Date: 2021-09-21
• Subjects: Magnesium alloys -- Hydrogen storage performance -- LPSO phases -- In-situ catalysts -- Pinning effect -- First-principles calculations; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2021.07.140
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: In this work, the as-cast Mg-rich Mg98.5 Gd1 Zn0.5 and Mg98.5 Gd0.5 Y0.5 Zn0.5 alloys are prepared by the semi-continuous casting method, and their hydrogen storage performance and catalytic mechanisms are investigated by experimental and first-principles calculations approaches. The results show that the LPSO phases decompose and in-situ form the RE(Gd/Y)H x ( x = 2, 3) nano-hydrides upon hydrogenation. These nano-hydrides not only serve as the in-situ catalysts to promote the hydrogen ab/desorption of Mg matrix, but also present the pinning effect to inhibit the growth of Mg/ MgH2 grains during hydrogenation and dehydrogenation. Comparatively, the two alloys exhibit the similar hydrogen absorption kinetics, while the hydrogen desorption kinetics of Mg98.5 Gd1 Zn0.5 is superior to that of Mg98.5 Gd0.5 Y0.5 Zn0.5 . The first-principles calculations reveal that the GdH2 and YH2 hydrides exhibit different catalytic effects on weakening the bond strength of H–H within H2 and Mg–H within MgH2, which interprets well the differences in the hydrogen ab/desorption kinetics between Mg98.5 Gd1 Zn0.5 and Mg98.5 Gd0.5 Y0.5 Zn0.5 alloys. Highlights: The Mg-rich Mg-Gd-Zn and Mg-Gd-Y-Zn alloys are prepared by semi-continuous casting. The LPSO phases decompose and in-situ form RE(Gd/ Y)H x ( x = 2, 3) upon hydrogenation. The RE(Gd/Y)H x ( x = 2, 3) show in-situ catalytic and pinning effects on Mg alloys. The desorption rate of Mg98.5 Gd1 Zn0.5 is faster than that of Mg98.5 Gd0.5 Y0.5 Zn0.5 . The GdH2 and YH2 both weaken the bond strength of H–H within H2 and Mg–H with MgH2 .