First-Principles Molecular Dynamics Studies of the Mechanisms and Characteristics of Hydrogen Storage in Carbon Nanomaterials

• Main Authors: Chih-Hao Wang, 王致皓
• Other Authors: 劉柏良
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/75xa76

碩士 === 國立中興大學 === 精密工程學系所 === 99 === In this paper, we use first-principles molecular dynamics studies of the mechanisms and characteristics of hydrogen storage in carbon nanomaterials. This research is divided into two categories: the effect of methyl radical on hydrogen storage of carbon nanotube and fullerene cage hydrogen storage. The simulate study include: structural differences, parameter setting, temperature regulation, electron density, and transition state. For calculations on hydrogen molecule adsorption on carbon nanotubes, the results indicate when a methyl radical in the space, that absorption energy of H2 on carbon nanotubes is decreased from 1.51eV to 0.49eV. We also comparison of the platinum catalyst and the four kinds of transition metal used as catalyst (such as: Ca, Pd, Sc, Ti) on the carbon nanotubes. The adsorption decreases significantly with the existence methyl radical. The electronic density shows that when the methyl radicals near the vicinity of hydrogen molecules, the hydrogen molecules and the catalyst for the charge density will be redistribution. Part of the electron transfer from the catalyst to the methyl radicals. This phenomenon will cause the catalysts to decrease influence of hydrogen molecule. The adsorption decreases significantly with the existence methyl radical. The hydrogen storage capacity also decreased from 3.35 wt% to 1.36 wt%. For calculation results on fullerene cage hydrogen storage, good agreement the computed existing data obtained from literature indicates that are presented in this paper is theoretically sound and practically applicable for the analysis of fullerene cage hydrogen storage systems. We clear and definite define the hydrogen storage capacity of four different fullerenes (such as: C60, C70, C80, C100). In addition, the molecular dynamics simulation results indicate. Fullerene elevated temperatures can reduce the transition state barrier high and the enhanced hydrogen storage capacity. Our calculations revealed that the most hydrogen storage capacity is 7.5 wt%. The results of these studies can provide new research directions for design of future hydrogen storage.