Hu Naiping, Sun Xiaoyang, Hsu Andrew
Department of Mechanical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, USA.
J Chem Phys. 2005 Jul 22;123(4):044708. doi: 10.1063/1.1954727.
Monte Carlo simulations and Widom's test particle insertion method have been used to calculate the solubility coefficients (S) and the adsorption equilibrium constants (K) in single-walled (10,10) armchair carbon nanotubes including single nanotubes, and nanotube bundles with various configurations with and without alkali dopants. The hydrogen adsorption isotherms at room temperature were predicted by following the Langmuir adsorption model using the calculated constants S and K. The simulation results were in good agreement with experimental data as well as the grand canonical Monte Carlo simulation results reported in the literature. The simulations of nanotube bundle configurations suggest that the gravimetric hydrogen adsorption increases with internanotube gap size. It may be attributed to favorable hydrogen-nanotube interactions outside the nanotubes. The effect of alkali doping on hydrogen adsorption was studied by incorporating K+ or Li+ ions into nanotube arrays using a Monte Carlo simulation. The results on hydrogen adsorption isotherms indicate hydrogen adsorption of 3.95 wt% for K-doping, and 4.21 wt% for Li-doping, in reasonable agreement with the experimental results obtained at 100 atm and room temperature.
蒙特卡罗模拟和维登测试粒子插入法已被用于计算单壁（10,10）扶手椅型碳纳米管（包括单根纳米管以及具有各种构型、有或没有碱掺杂剂的纳米管束）中的溶解度系数（S）和吸附平衡常数（K）。通过使用计算得到的常数S和K，依据朗缪尔吸附模型预测了室温下的氢吸附等温线。模拟结果与实验数据以及文献中报道的巨正则蒙特卡罗模拟结果吻合良好。纳米管束构型的模拟表明，重量氢吸附量随纳米管间间隙尺寸的增大而增加。这可能归因于纳米管外部有利的氢 - 纳米管相互作用。通过蒙特卡罗模拟将K⁺或Li⁺离子纳入纳米管阵列，研究了碱掺杂对氢吸附的影响。氢吸附等温线的结果表明，K掺杂时氢吸附量为3.95 wt%，Li掺杂时为4.21 wt%，与在100 atm和室温下获得的实验结果合理吻合。
