氢在多壁碳纳米管上的等量吸附热

为说明氢在多壁碳纳米管(MWCNTs)上所受吸附作用的强弱,文中基于氢和77 K氮的吸附数据,比较了由非局域密度泛函理论(NDFT)、等量吸附线和归一化等温线线性化确定的等量吸附热。结果表明,氢在MWCNTs上等量吸附热随温度变化且表现出在弱的能量不均匀表面吸附的特点,平均值约为3—4 kJ/mol;由77 K氮吸附等温线确定的孔大小分布(PSD)和比表面积影响NDFT计算初始吸附时的精度;在吸附量和吸附温度都较低时,等量吸附线标绘结果与归一化等温线线性化方程确定的等量吸附热之间的偏差较小,在200—290 K温度区间则与ND-FT计算结果更为接近。然而,当温度大于310 K时,3种方法计算结果间的偏差较大。

Isosteric heat of hydrogen adsorption on multi-walled carbon nanotubes

For studying the adsorptive performance of hydrogen molecules on carbon nanostructures,the isosteric heat of hydrogen adsorption on Multi-walled Carbon Nanotubes(MWCNTs) was determined by comparison of the results from Non-local Density Functional Theory(NDFT) calculation,adsorption isosteres and the linearized equation.The results show that the isosteric heat is in characteristic of the weak temperature dependence and the adsorption on an energy heterogeneous surface,the mean isosteric heat is about 3-4 kJ/mol.In a lower surface coverage region,the results from NDFT calculation deviate from those by adsorption isosteres;at 200-290 K,the results from adsorption isosteres are more comparable to those by NDFT calculation than those from the linearized equation.However,when temperature is above 310 K,the discrepancies among the calculation results by above mentioned approaches are considerable.