结构与尺寸对碳纳米管物理吸附储氢的影响

采用巨正则蒙特卡罗方法,在298K和10MPa下,系统地研究了碳纳米管及其阵列的物理吸附储氢量与单壁管的管径、多壁管的层间距和管层数、单壁管阵列的管间距和排列方式的关系.发现单壁管的管径等于6nm时,管内的储氢密度达到最大;多壁管的层间距由034nm增大至061或088nm时,物理吸附储氢量明显增大;单壁管阵列的管间距等于17nm时,其管外间隙处的储氢密度达到最大,且方阵阵列优于三角阵列;当单壁管阵列的管间距大于06nm时,其管外的储氢密度均大于管内的储氢密度.指出合理地选择单壁管的管径、多壁管的层间距、单壁管阵列的管间距和排列方式,可以有效地提高碳纳米管及其阵列的物理吸附储氢量,并给出了相应的理论解释.

Effects of Carbon Nanotube Structure and Size on Hydrogen Physisorption

Grand canonical Monte Carlo(GCMC) method is adopted to investigate the dependence of hydrogen storage capacity on the diameter of a single-walled carbon nanotube(SWCNT), the distance between walls and the shell number of a multi-walled carbon nanotube(MWCNT),as well as the inter-tube distance and configuration of SWCNT array(SWCNTA),at 298K and 10MPa.The calculated results show that when the diameter of SWCNT approaches 6 nm the average number density(n-{AV}) of hydrogen within the tube reaches its maximum.When the difference between the internal radius and the external radius increases from 0^34 to 0^61 or 0^88 nm the hydrogen storage capacity is improved effectively.As the inter-tube distance of SWCNTA approaches 1^7 nm n-{AV} within the interstitial space of SWCNTA reaches its maximum and a square array is better than a triangular array for hydrogen physisorption.It is also found that n-{AV} within the interstitial space is larger than that within the tube whether for a square array or a triangular array,only if inter-tube distance is larger than 0^6 nm.The hydrogen storage capacity could be effciently increased by the reasonable choice of the diameter of SWCNT,the distance between walls of MWCNT,the inter-tube distance and configuration of SWCNTA.Conclusions are discussed and explained.