Hydrogen Storage Properties of Nanosized MgH2-0.1TiH2 Prepared by Ultrahigh-Energy-High-Pressure Milling
Hydrogen Storage Properties of Nanosized MgH2-0.1TiH2 Prepared by Ultrahigh-Energy-High-Pressure Milling
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DOI：
10.1021/ja906340u
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发表时间：
2009-11-04
影响因子：
15
通讯作者：
Roennebro, Ewa
中科院分区：
文献类型：
--
作者：
Lu, Jun;Choi, Young Joon;Roennebro, Ewa
氢化镁 (MgH2) 是固态储氢应用的一个有吸引力的候选者。为了改善MgH2在脱氢-再氢化循环过程中的动力学和热力学性质，研究了通过超高能高压机械研磨制备的纳米结构MgH2-0.1TiH(2)材料体系。高分辨率透射电子显微镜(TEM)和扫描TEM分析表明，研磨后的MgH2-0.1TiH(2)粉末的晶粒尺寸约为5-10 nm，TiH2在MgH2颗粒之间分布均匀。压力-成分-温度 (PCT) 分析表明，与商用 MgH2 相比，纳米尺寸和 TiH2 的添加都有助于显着改善脱氢和氢化动力学。更重要的是，PCT循环分析表明MgH2-0.1 TiH2材料体系表现出优异的循环稳定性。结果还表明，纳米结构MgH2-0.1TiH(2)脱氢的Delta H值显着低于商业MgH2。然而，反应的AS值也较低，这导致纳米尺寸和TiH2的添加对MgH2脱氢反应平衡压力的净影响最小。
Magnesium hydride (MgH2) is an attractive candidate for solid-state hydrogen storage applications. To improve the kinetics and thermodynamic properties of MgH2 during dehydrogenation-rehydrogenation cycles, a nanostructured MgH2-0.1TiH(2) material system prepared by ultrahigh-energy-high-pressure mechanical milling was investigated. High-resolution transmission electron microscope (TEM) and scanning TEM analysis showed that the grain size of the milled MgH2-0.1TiH(2) powder is approximately 5-10 nm with uniform distributions of TiH2 among MgH2 Particles. Pressure-composition-temperature (PCT) analysis demonstrated that both the nanosize and the addition of TiH2 contributed to the significant improvement of the kinetics of dehydrogenation and hydrogenation compared to commercial MgH2. More importantly, PCT cycle analysis demonstrated that the MgH2-0.1 TiH2 material system showed excellent cycle stability. The results also showed that the Delta H value for the dehydrogenation of nanostructured MgH2-0.1TiH(2) is significantly lower than that of commercial MgH2. However, the AS value of the reaction was also lower, which results in minimum net effects of the nanosize and the addition of TiH2 on the equilibrium pressure of dehydrogenation reaction of MgH2.