The Dehydrogenation Mechanism and Cycling Property of MgH2 Modified by CoB/CNTs Addition
The Dehydrogenation Mechanism and Cycling Property of MgH2 Modified by CoB/CNTs Addition
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CoB/CNTs改性MgH2的脱氢机理及循环性能
DOI：
10.1002/slct.201902520
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Yan Mi
中科院分区：
文献类型：
--
作者：
Gao Shichao;Wang Xinhua;Liu Haizhen;He Ting;Li Shouquan;Yan Mi
本文采用X射线衍射（XRD）研究了MgH2+10 wt% CoB/CNTs在不同温度下的脱氢过程。结果表明，当温度从室温升高到500℃时，部分CoB/CNTs可能与mgh2反应形成新相Co3MgC。此外，还发现MgH2+10 wt% CoB/CNTs和MgH2的脱氢过程分别受三维相边界和一维扩散动力学机制的控制。这种差异归因于原位形成的Co3MgC可以提供许多途径，并作为加速氢解离和结合的“氢泵”。此外，还研究了MgH2+10 wt% CoB/CNTs复合材料的循环性能。在6个循环周期内，储氢容量和吸氢动力学保持稳定。在300℃下，MgH2+10 wt% CoB/CNTs可在约40 min内稳定释放约6.3 wt%的h2o2，并可快速完成吸氢。XRD测试表明，Co3MgC在循环6次后仍保持不变，这对循环稳定性有积极的影响。
In this paper, the dehydrogenation process of MgH2+10 wt% CoB/CNTs was studied by X‐ray diffraction (XRD) at various temperatures. The results indicated that a part of CoB/CNTs might react with MgH2to form the new phase Co3MgC as the temperature increases from room temperature to 500 °C. Furthermore, it was found that the hydrogen desorption processes of the MgH2+10 wt% CoB/CNTs and as‐milled MgH2were controlled by the three‐dimensional phase boundary and the one‐dimensional diffusion kinetic mechanism, respectively. This difference is attributed to the fact that the in‐situ formed Co3MgC can provide many pathways and act as “hydrogen pumps” for accelerating the hydrogen dissociation and association. Moreover, the cycling property of the MgH2+10 wt% CoB/CNTs composite was also studied. The hydrogen storage capacity and the hydrogen de/absorption kinetics can remain stable over 6 cycles. MgH2+10 wt% CoB/CNTs can steadily release about 6.3 wt% of H2within about 40 min at 300 °C, and hydrogen absorption can be completed rapidly. XRD measurements show that Co3MgC remains unchanged after 6 cycles, which has positive effect on the cycling stability.