Improved hydrogen storage performances of MgH2–NaAlH4 system catalyzed by TiO2 nanoparticles
Improved hydrogen storage performances of MgH2–NaAlH4 system catalyzed by TiO2 nanoparticles
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DOI：
10.1016/j.jallcom.2014.03.150
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发表时间：
2014-08
影响因子：
6.2
通讯作者：
Rafi-ud-din;Qu Xuanhui;G. H. Zahid;Z. Asghar;M. Shahzad;M. Iqbal;E. Ahmad
中科院分区：
文献类型：
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作者：
Rafi-ud-din;Qu Xuanhui;G. H. Zahid;Z. Asghar;M. Shahzad;M. Iqbal;E. Ahmad
研究了TiO2纳米粒子的添加对MgH2-NaAlH4(摩尔比1:2、1:1和2:1)复合材料吸氢性能和反应机理的影响。结果表明，TiO2纳米颗粒在改善MgH2-NaAlH4复合材料的脱氢/再氢化动力学和降低脱氢温度方面具有积极作用。等温体积测量表明，掺杂 TiO2 样品的动力学分别是未掺杂二元样品和 MgH2 样品的 1.5 倍和 6 倍。掺杂样品显示 NaAlH4、Na3AlH6、MgH2 和 NaH 相关分解的活化能显着降低。 TiO2 掺杂还显着增强了二元复合材料的可逆容量，在三个脱氢/再氢化循环中持续良好。 XRD、XPS 和 FESEM-EDS 分析表明，在第一次解吸过程中形成的精细分散的缺氧钛物质在循环过程中迁移到复合材料的本体中。有人建议，这些精细分散的缺氧钛物质可能通过充当活性位点来促进脱氢/再氢化过程中的氢扩散，从而有助于动力学改进。
The effects of addition of TiO2nanoparticles on the hydrogen sorption properties and reaction mechanism of MgH2–NaAlH4(mole ratios 1:2, 1:1 and 2:1) composites were investigated. The results indicated that TiO2nanoparticles were active in improving the dehydriding/rehydriding kinetics and reducing the dehydrogenation temperature of MgH2–NaAlH4composite. Isothermal volumetric measurements revealed that the kinetics of TiO2doped samples were 1.5 and 6 times that of undoped binary and MgH2samples. The doped sample displayed substantially reduced activation energies for NaAlH4, Na3AlH6, MgH2, and NaH relevant decompositions. TiO2doping had also markedly enhanced the reversible capacity of binary composites, persisting well during three dehydrogenation/rehydrogenation cycles. XRD, XPS, and FESEM–EDS analyses had demonstrated that finely dispersed oxygen-deficient titanium species, formed during the first desorption, were migrated to the bulk of composite during cycling. It was suggested that these finely dispersed oxygen-deficient titanium species might contribute to kinetic improvement by serving as active sites to facilitate the hydrogen diffusion during dehydrogenation/rehydrogenation processes.