X.Yao
,
C.Z.Wu
,
H.Wang
,
H.M.Cheng
,
G.Q.Max Lu
材料科学技术（英）
Hydrogen storage in traditional metallic hydrides can deliver about 1.5 to 2.0 wt pct hydrogen but magnesium hydrides can achieve more than 7 wt pct. However, these systems suffer from high temperature release drawback and chemical instability problems. Recently, big improvements of reducing temperature and increasing kinetics of hydrogenation have been made in nanostructured Mg-based composites. This paper aims to provide an overview of the science and engineering of Mg materials and their nanosized composites with nanostructured carbon for hydrogen storage. The needs in research including preparation of the materials, processing and characterisation and basic mechanisms will be explored. The preliminary experimental results indicated a promising future for chemically stable hydrogen storage using carbon nanotubes modified metal hydrides under lower temperatures.
关键词:
Hydrogen storage
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null
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null
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null
Lianquan GUO
,
Changxiang MA
,
Shuai WANG
,
He MA
,
Xin LI
材料科学技术（英）
The adsorption of hydrogen onto single-walled carbon nanotubes (SWCNTs) was studied by molecular dynamics (MD) simulation. It was found that the hydrogen molecules distribute regularly inside and outside of the tube. Density distribution was computed for H2 molecule. Theoretical analysis of the result showed the multilayer adsorption mechanism of SWCNTs. The storage of H2 in SWCNTs is computed, which provides essential theoretical reference for further study of hydrogen adsorption in SWCNTs.
关键词:
Single-walled carbon nanotubes
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null
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Dong CHEN
,
Jingdong CHEN
,
Yinglu ZHAO
,
Hailiang HUO
,
Benhai YU
,
Deheng SHI
金属学报(英文版)
doi:10.1016/S1006-7191(08)60106-4
The crystal and electronic structures of LaNi4.75Sn0.25 intermetallics and LaNi4.5Sn0.5Hy (y=2.0, 2.5) intermediate phase have been investigated by the full-potential linearized augmented plane wave (FP-LAPW) method. Hydrogen occupation sites in LaNi4.5Sn0.5Hy have been determined based on Westlake$'$s criterions: (1) the minimum hole radius is 0.04~nm; (2) the minimum H-H distance is 0.21~nm; as well as geometry optimizations and internal coordinates optimizations. We find that hydrogen atoms prefer to occupy the 12n*, 6m, 12o, 6m* sites in LaNi4.5Sn0.5H2.0 and the 6m*, 4h, 6m, 12o, 12n* sites in LaNi4.5Sn0.5H2.5. The specific coordinates of hydrogen atoms in LaNi4.5Sn0.5Hy are also determined. The results show that hydrogen atoms tend to keep away from tin atoms. The maximum hydrogen content decreases compared with LaNi5. The interactions between Sn and Ni with H play a dominate role in the stability of LaNi4.5Sn0.5-H system. Lattice expansion and increment of Fermi energy E F show that both Sn and H atoms decrease structural stability of these alloys.
关键词:
Rare-earth intermetallics
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null
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苏伟
,
周亚平
,
魏留芳
,
孙艳
,
周理
新型炭材料
doi:10.3969/j.issn.1007-8827.2007.02.008
研究了椰壳基活性炭微孔结构和化学改性对其储氢能力的影响.结果表明,物理活化的椰壳基活性炭用HF或NH3·H2O处理后可提高活性炭的吸氢能力,用HNO3处理后吸氢能力几乎没有什么变化,而用H3PO4处理后吸氢能力却有明显的下降.活性炭的比表面积、孔径分布和表面性质都会影响其吸附氢气的能力,其中,比表面积是最主要的影响因素.
关键词:
活性炭
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微孔结构
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表面改性
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储氢
Zhongmin WANG
,
Huaiying ZHOU
,
R.P.ZOU
,
Zhengfei GU
材料科学技术（英）
Mg1.95RE0.05Ni (RE=La, Ce, Pr, Nd, Y), REMgNi4 (RE=La, Ce, Pr, Nd) and REMg2Ni9(RE=Pr, Nd) compounds were prepared by ball-milling of mixed powder of Mg, Ni, RENi (or RE) followed by sintering in pure Ar. XRD analysis showed that Mg1.95RE0.05Ni compounds are all single-phase with a crystal structure same as Mg2Ni. The lattice constants (a, c, c/a) were calculated. It was suggested that rare earth substitution leads to a slight increase in the values of a and c compared with Mg2Ni. Electrode properties of these compounds were evaluated by means of a simulated battery test. The effectiveness in improving the discharge capacity resulted from the addition of RE increased in the following order: Mg1.95Pr0.05Ni>Mg1.95Nd0.05Ni>Mg1.95Ce0.05Ni>Mg1.95La0.05Ni>Mg1.95Y0.05Ni. For REMgNi4 compounds, a slight increase in the discharge capacity was observed in the following order: NdMgNi4>PrMgNi4>La- MgNi4>CeMgNi4. The maximum discharge capacity of NdMgNi4 compound was about 200 mAh/g. The discharge capacities of both NdMg2Ni9 and PrMg2Ni9 compounds were less than 100 mAh/g.
关键词:
Mg-Ni-RE compounds
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