Catalytic effect of in situ formed nano-Mg2Ni and Mg2Cu on the hydrogen storage properties of Mg-Y hydride composites

• Published in: Journal of alloys and compounds Vol. 782; pp. 242 - 250
• Main Authors: Xu, Cheng, Lin, Huai-Jun, Wang, Yunlei, Zhang, Peng, Meng, Yuying, Zhang, Yao, Liu, Yana, Zhang, Jiguang, Li, Liquan, Shi, Qian, Li, Wei, Zhu, Yunfeng
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25.04.2019; Elsevier BV
• Subjects: Alloys; Amorphous alloys; Catalysis; Catalytic effect; Cracks; Dehydrogenation; Hydrides; Hydrogen; Hydrogen storage; Hydrogenation; Kinetics; Melt spinning; Metallic glasses; Mg-based alloys; Nanocomposites; Nanoparticles; Particle size distribution; Properties (attributes); Reaction kinetics; Catalytic effect; Mg-based alloys; Melt spinning; Hydrogen storage; Kinetics
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2018.12.223

Two hydrides nanocomposites, consisting of MgH2-Mg2NiH4-YH2 and MgH2-MgCu2-YH2 phases, were prepared by hydrogenation upon the melt-spun Mg80Y5Ni15 and Mg80Y5Cu15 amorphous alloys, respectively. The catalytic effect of nano-Mg2Ni/Mg2NiH4 and Mg2Cu/MgCu2 particles on hydrogen storage properties of Mg-Y hydride composites have been studied. It is shown that the activated melt-spun Mg80Y5Ni15 alloy exhibits higher hydrogen absorption capacity and faster hydriding/dehydriding kinetics than those of the activated melt-spun Mg80Y5Cu15 alloy. The activated melt-spun Mg80Y5Ni15 alloy absorbs about 4.2 wt% hydrogen in 10 min at 200 °C, and almost fully desorbs hydrogen within 5 min at 280 °C. In contrast, the activated melt-spun Mg80Y5Cu15 alloy absorbs about 4 wt % of hydrogen in 2 h  at 280 °C, and desorbs 3.7 wt% of hydrogen in 80 min at 300 °C. The apparent activation energy of dehydrogenation for the activated melt-spun Mg80Y5Ni15 alloy was calculated to be 83.9 kJ/mol, which is significantly lower than that of 132.3 kJ/mol for the activated melt-spun Mg80Y5Cu15 alloy. The excellent hydrogen storage properties of the activated melt-spun Mg80Y5Ni15 alloy can be attributed to the multiple cracks and refined particle size generated during hydrogenation, and the uniform distributed catalytic Mg2Ni/Mg2NiH4 nanoparticles in the Mg/MgH2 matrix. In contrast, a large amount of Mg2Cu/MgCu2 phase significantly aggregations, and the separation between Mg2Cu/MgCu2 and Mg/MgH2 matrix in the activated melt-spun Mg80Y5Cu15 alloy, which greatly decrease the catalytic effect of Mg2Cu for the activated melt-spun Mg80Y5Cu15 alloy. •Hydrogen storage properties of melt-spun Mg-Y-X (X = Cu, Ni) alloys are studied.•Catalytic effects of the in situ formed Mg2NiH4 and Mg2Cu/MgCu2 are compared.•Ni shows much better catalytic effect on improving hydrogen storage properties that Cu.