De-/re-hydrogenation features of NaAlH4 confined exclusively in nanopores
De-/re-hydrogenation features of NaAlH4 confined exclusively in nanopores
复制标题
NaAlH4 的脱/再氢化特征仅局限于纳米孔中
DOI：
10.1016/j.actamat.2010.11.049
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发表时间：
2011-02-01
期刊：
影响因子：
9.4
通讯作者：
Sun, D.
中科院分区：
文献类型：
--
作者：
Li, Y.;Zhou, G.;Sun, D.
在目前的工作中，通过三步程序合成了NaAlH4专门嵌入有序介孔碳（MC）中的纳米限制系统，即热熔融浸渍加脱/再氢化。结果表明，MC 内的 NaAlH4 表现出比原始 NaAlH4 更快的脱氢动力学，活化能降低了约 70 kJ mol(-1)。 15 次脱氢/再氢化循环后，容量保持率仍高达 80% 以上，从而增强了循环稳定性。这些显着的改进归因于纳米限制和MC引起的化学催化的协同效应，其中纳米限制发挥主导作用。此外，动力学模型研究表明，限域NaAlH4体系中的氢释放受两个过程控制：初始过程可以通过一维成核和生长来表达，第二个过程由三维扩散和相界迁移共同控制。 (C) 2010 Acta Materialia Inc. 由 Elsevier Ltd 出版。保留所有权利。
In the present work, a nanoconfinement system with NaAlH4 exclusively embedded in ordered mesoporous carbon (MC) was synthesized by a three-step procedure, i.e., thermal melting impregnation plus de-/re-hydrogenation. It is demonstrated that the NaAlH4 inside MC shows faster kinetics for dehydrogenation than the kinetics of pristine NaAlH4 with a reduction in activation energy by similar to 70 kJ mol(-1). An enhanced cycling stability is also achieved by the high-capacity retention of >80% after 15 de-/re-hydrogenation cycles. These remarkable improvements are attributed to the synergistic effects of both nanoconfinement and chemical catalysis caused by the MC, where nanoconfinement plays a dominant role. Furthermore, kinetic modeling studies suggest that the hydrogen release from the confined NaAlH4 system is governed by two processes: the initial process can be expressed by one-dimensional nucleation and growth, and the second process is jointly controlled by three-dimensional diffusion and phase boundary migration. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.