The Migration Properties Research Of Water And Across The Modified Carbon Nanotube

With the development of economy,the global energy crisis is becoming increasingly apparent,and the demand of new energy sources is urgent.Fuel cell as a highly efficient pollution-free energy has been achieved a great deal of attention,Its high price hindered the large-scale commercial use of fuel cell.Although in many theories the structure of carbon nanotubes is described as an open structure,it is necessary to add molecular functional groups [such as hydrogen atom(-H),hydroxyl(-OH),carboxyl(-COOH)] to the dangling bonds of the port to form a stable structure.The molecular topological structure and the distribution of the electron cloud at the modified port of carbon nanotubes affect the migration properties of the particles at the port.The reaction products of fuel cell mainly includes water and carbon dioxide.Therefore,the research focus of this paper is to analyze the morphological structure(such as the diameter of carbon nanotubes,the types of port functional groups and the external field conditions(such as temperature and electric field)using molecular dynamics simulation method.Migration properties of water molecules and carbon dioxide at functionalized carbon nanotube ports.The construction diameters are 8.14? [CNT(6,6)],10.85? [CNT(8,8)],13.56 ? [CNT(10,10)],16.27 ?CNT [(12,12)],18.98? [ CNT(14,14)],and three different functional groups,H,OH and-COOH,were charged with 1.0 g / cm3 of water molecules and 1.429 g / cm3,respectively,The carbon nanotubes and the functional groups were analyzed for the migration properties of water molecules and carbon dioxide molecules at the carbon nanotube ports.The results show that when the diameter of carbon nanotubes increases,the frequency of water molecules and carbon dioxide increases through the functionalized carbon nanotubes,and is beneficial to adsorb water molecules and carbon dioxide.The effect of the three functional groups is different,and the resistance of carboxyl groups The largest,mainly because it has a longer chain length compared to the other two functional groups.However,the effect of hydrogen and hydroxyl groups will change with the diameter of carbon nanotubes.When the diameter of carbon nanotubes is small,the swinging degree of hydrogen groups in the ports is much greater than that of carboxyl groups,so the effective flow area is reduced,When the carboxyl group at this time is more conducive to the diffusion of water molecules and carbon dioxide,but when the diameter of carbon nano increases,although the hydrogen group swing speed is greater than the carboxyl group,but the carboxyl chain longer,this time it is the main determinant,So the hydrogen group is more conducive to the diffusion of water molecules and carbon dioxide;with the increase of carbon nanotubes,water molecules and carbon dioxide in the carbon nanotubes within the formation of different ring arrangement,and gradually close to the disorder state,which It is shown that with the increase of the diameter of carbon nanotubes,it gradually approaches the natural state inside the carbon nanotubes.We select the port modification is-H carbon nanotubes and analysize the effects of temperature effects.The results show that the frequency of water molecules and carbon dioxide through the functionalized carbon nanotube ports increases with the increase of temperature,but the temperature is more obvious for the diffusion of water molecules at the port.The number of water molecules and carbon dioxide adsorbed in carbon nanotubes has found that the adsorption of water and carbon dioxide in carbon nanotubes has almost no change with increasing temperature,indicating that the increase in temperature does not lead to water molecules And carbon dioxide in the carbon nanotubes in the structural changes.With the increase of temperature,the thermal motion of the whole system is enhanced,and the diffusion coefficient of water molecules and carbon dioxide increases.This indicates that the increase of temperature is beneficial to the diffusion of water molecules and carbon dioxide in carbon nanotubes.We select the port modification is-H carbon nanotubes and study the impact of the electric field.The results show that when the diameter of carbon nanotubes is the same,the frequency of water molecules and carbon dioxide migrating functionalized carbon nanotubes increases with the increase of electric field intensity,which indicates that the increase of electric field strength is favorable for water and carbon dioxide to pass through functional groups Carbon nanotube ports.When the electric field is applied,the polarization of the water molecules occurs in the carbon nanotubes due to the presence of the electric field,which causes the structure of the water molecules to change in the carbon nanotubes,but it does not cause the polarization of the carbon dioxide.Will lead to structural changes in the carbon nanotubes.When the diameter of carbon nanotubes is the same,the diffusion ability of water molecules and carbon dioxide in carbon nanotubes increases with the increase of electric field strength,which indicates that the applied electric field forms a favorable diffusion of water molecules and carbon dioxide in carbon nanotubes Conditions,and thus enhance the water molecules and carbon dioxide diffusion coefficient.