期刊
ACS APPLIED MATERIALS & INTERFACES
卷 11, 期 42, 页码 38868-38879出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.9b16076
关键词
magnesium hydride; hydrogen storage material; amorphous alloy; catalyst; kinetics
资金
- National Natural Science Funds for Young Scientists of China [51704336]
- Hunan Provincial Natural Science Foundation of China [2018D3653]
- Powder Metallurgy Laboratory in the Department of Metallurgical Engineering of the University of Utah
- U.S. Department of Energy (DOE)
- Office of Energy Efficiency and Renewable Energy
- Vehicle Technologies Office
- U.S. DOE [DE-AC02-06CH11357]
Magnesium hydride has long been regarded as a promising candidate material for hydrogen and heat storage due to its high hydrogen capacity, reversibility, and low cost. Catalytic doping has been demonstrated as one of the most effective methods to improve hydrogen storage properties of MgH2. In this study, amorphous Ti45Cu41Ni9Zr5 and Ti40Cu47Zr10Sn3 alloys are used as additives for MgH2. Nanostructured MgH2 doped with amorphous or crystalline TiCu-based alloys are prepared by using a high-energy mechanochemical synthesis method. Results show that the amorphous TiCu additives provide enhanced catalytic effects compared to crystalline alloys of the same composition. Doping MgH2 using an amorphous Ti45Cu41Ni9Zr5 alloy yielded improved dehydrogenation kinetics compared to using crystalline Ti40Cu47Zr10Sn3 alloy. The analysis using transmission electron microscopy reveals that there are nanostructured catalytic particles uniformly distributed in the amorphous TiCu-catalyzed MgH2. The MgH2 system catalyzed by amorphous TiCu-based alloy shows little degradation during hydrogenation and dehydrogenation cycling at 300 degrees C. The amorphous TiCu-based catalysts are thermally stable at temperatures up to 360 degrees C. Heating the amorphous Ti45Cu41Ni9Zr5-catalyzed MgH2 to temperatures above 360 degrees C led to disproportionation of the catalyst alloy and the formation of MgCu2 and Ti2Cu. In addition, PCI analysis of the amorphous Ti45Cu41Ni9Zr5-catalyzed MgH2 shows a slight increase in hydrogen equilibrium pressure, resulting in a reaction enthalpy of -78.7 kJ/mol.H-2 and an entropy of 145.0 J/K.mol.H-2. The entropy calculated from this study is approximately 10 J/K.mol.H-2 higher than values previously reported for undoped and catalyzed Mg-H systems.
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