Computer Simulation Of Hydrogen Storage In Transition Metal-doped Single-walled Carbon Nanotube Array

Firstly, the significance of investigation on hydrogen storage in carbon nanotubes (CNTs) is indicated, and the hydrogen storage capacity of CNTs can be enhanced obviously by transition metal-doping.Secondly, the structure and absorption characteristic of CNTs are introduced and the developments of experimental and theoretical researches for hydrogen storage in CNTs are compared with that in transition metal doped CNTs.Thirdly, three transition metal-doping schemes are presented on the basis of recent scientific research. And then, the properties of hydrogen physisorption in transition metal-doped SWCNTA (transition metal-doped single-walled carbon nanotube array) are investigated by GCMC (grand canonical Monte Carlo) method, at room temperature and moderate pressure. The computational results show that the hydrogen storage capacity of SWCNTA can be enhanced efficiently by transition metal-doping, and the influence of the transition metal atoms'doped sites, doped concentration and doped element on the actual doping effect is remarkable. Based on these, the best doping scheme is indicated. By analyzing the changes of electronic structure and potential wells of SWCNTA before and after transition metal-doping, the qualitative and quantitative explanations for hydrogen storage capacity of SWCNTA can be enhanced efficiently by transition metal-doping are given.At last, influence of structure and size of transition metal-doped SWCNTA on hydrogen physisorption is investigated by varying tube diameter and distance between tubes synchronously. A great deal of our computational results show that the hydrogen storage capacity of Ni-doped SWCNTA can be enhanced more efficiently in comparison with alkali-metal doped SWCNTA, because there is a unique hybridization between Ni-d and SWCNT C-p orbit. And the results also indicate that at normal temperature and moderate pressure with the best doping scheme and the reasonable control of SWCNTA's structure and size, the hydrogen storage capacity of transition metal-doped SWCNTA can reach and exceed the 2015 target, which is presented by U.S. Department of Energy.