The Properties Of Physisorption And Chemiadsorption Of Hydrogen Stored In Multi-walled Carbon Nanotubes

The experimental and theorical researches of hydrogen storage in carbon nanotubes(CNTs) since 1997 were firstly reviewed in this article , main experimental and theorical results have been generalized . Two main approaches of theorical study on hydrogen storage in CNTs were introduced as follows: 1. Grand Canonical Monte Carlo (GCMC) method based on all kinds of potential functions . 2. quantum Molecular Dynamics(MD) based on density functional theory (DFT) etc .Secondly , by adopting GCMC and Lennard-Jones(L-J) potential model, we simulated the physisorption of hydrogen in multi-walled carbon nanotubes (MWCNTs). The relation of the physisorption capicity of hydrogen in MWCNTs and the wall-wall distance > the diameters of tubes N the number of wall has been investigated systematically, some conclusions were obtained as follows: If the wall-wall distance is changed from 0.34nm to 0.61nm and 0.88~0.95nm , the storage capicity of hydrogen in MWCNTs will be effectively improved ; the physisorption capicity of hydrogen in MWCNTs is proportional to the interior tube diameters ; the physisorption capicity of hydrogen in MWCNTs decreases as the number of wall increasess ; when Fb is adsorbed in MWCNTs , the number of H2 near the walls of MWCNTs is generally more than that in internal space of tube ; the physisorption capicity of hydrogen in MWCNTs is not higher than that in single-walled carbon nanotubes(SWCNTs) ; hydrogen adsorption in the wall-wall distance 0.34nm of MWCNTs can not be explained by physisorption mechanism.Thirdly , by using Canonical Assemble Molecular Dynamics(CAMD) and quantum theory, we calculated the chemiadsorption of hydrogen in small MWCNTs , the results show that H atoms can bond C atoms of CNTs and are adsorbed on the interior and exterior surface of the tube walls , the chemiadsorption capicity of hydrogen in MWCNTs is independent of tube diameters . It is discovered that there are physisorption and chemiadsorption mechanism of hydrogen storage in MWCNTs.At last, the whole article was summarized and some expections of further study on hydrogen storage in MWCNTs were given .