First-principles study on hydrogen storage by graphitic carbon nitride nanotubes
First-principles study on hydrogen storage by graphitic carbon nitride nanotubes
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DOI：
10.1016/j.ijhydene.2011.11.109
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发表时间：
2012-03
影响因子：
7.2
通讯作者：
G. Koh;Yong-Wei Zhang;H. Pan
中科院分区：
文献类型：
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作者：
G. Koh;Yong-Wei Zhang;H. Pan
采用基于密度泛函理论的第一性原理计算方法研究了石墨化碳氮化碳纳米管的储氢性能。碳氮化碳纳米管具有良好的吸氢性有两个原因：第一，其多孔结构使氢容易进入纳米管内部；第二，其孔边的双键氮为氢的吸附(化学和物理)或金属催化剂功能化提供了活性中心。我们的计算表明，一个孤立的纳米管可以吸收高达4.66wt.%的氢，平均每个氢原子的总吸氢能约为−0.22 eV。由于增加了管子之间的空间可用性，所以以散装束的形式提高了储氢容量。我们预测，该束中的储氢容量至少为5.45wt.%。重要的是，氢分子可以很容易地进入管子内部，因为它们通过气孔的低能垒(∼0.54eV)，表明在相对较低的压力和温度下有较快的吸收速度。研究结果表明，石墨化碳氮纳米管具有较高的重量容量和较快的吸氢速率，可以应用于实际储氢。
First-principles calculations based on density functional theory were carried out to investigate the hydrogen storage capacity of graphitic carbon nitride nanotubes. Graphitic carbon nitride nanotubes could be attractive hydrogen sorbent for two reasons: firstly, its porous structure allows easy access of hydrogen into the interior of the nanotubes; and secondly, the doubly bonded nitrogen at its pore edges provides active sites for either the adsorption of hydrogen (chemically and physically), or functionalization with metal catalysts. Our calculations show that an isolated nanotube can uptake up to 4.66 wt. % hydrogen, with an average overall hydrogen adsorption energy of about −0.22 eV per H atom. In the form of a bulk bundle, the hydrogen storage capacity is enhanced due to the increased availability of space among the tubes. We predict that the hydrogen storage capacity in the bundle is at least 5.45 wt. %. Importantly, hydrogen molecules can easily access the tube’s interior due to the low energy barrier (∼0.54 eV) for their passage through the pores, indicating a fast uptake rate at relatively low pressure and temperature. Our findings show that graphitic carbon nitride nanotubes should be applicable to practical hydrogen storage because of the high gravimetric capacity and fast uptake rate.