椅型碳纳米管吸附氧原子的密度泛函理论研究

A density functional theory study of the absorption behavior of oxygen on single-walled carbon nanotubes

利用密度泛函B3LYP对有限长扶手椅形单壁碳纳米管(3,3),(4,4)和(5,5)吸附O原子的几何结构、电子属性、反应能和红外光谱进行了系统地理论研究,获得了一些有意义的结果,主要包括如下4个方面:(1)2个O原子吸附在管外壁垂直于管轴的C—C键形成开环的轮烯结构,吸附在管内壁形成环氧结构;(2)O原子吸附在管外壁要比吸附在管内壁具有较大的能隙和吸附反应能;(3)与单壁碳纳米管管外壁吸附1个O原子相比,2个O原子吸附在管外壁具有较大的吸附反应能;(4)B3LYP得到的C—O伸缩振动频率与实验一致.

The absorption behavior of oxygen atoms on the finite-length armchair single-walled carbon nanotubes of（3,3）,（4,4） and（5,5） has been investigated by means of the B3LYP hybrid density functional method using 6-31G＊ basis set.The geometrical structures,electronic properties and thermal stabilities as well as vibrational frequencies of the systems considered are studied.The results show that the absorption on the outside nanotube with a vertical orientation to the tube axis has an annulene-like structure,while the absorption on the inside nanotube has an epoxide-like structure.Exohedral nanotube adsorption is energetically more favorable than endohedral adsorption.Compared with chemisorption of one oxygen atom,the chemisorption of two oxygen atoms on the outside nanotube increases the reaction energy of corresponding complexes.The calculated C—O stretching frequencies of（3,3）,（4,4） and（5,5） nanotubes are in good agreement with the available experimental results.