异性官能团修饰石墨烯吸附GIS 特征气体能力的DFT研究

为研制高灵敏度气体绝缘组合开关(GIS)特征气体检测传感器,利用密度泛函理论方法,采用分子模拟软件对GIS特征气体(SO_2,SOF_2,SO_2F_2,CF_4)在异性官能团(羟基、羧基与氨基)修饰石墨烯表面的吸附过程进行模拟计算,从微观角度研究了GIS特征气体在异性官能团修饰石墨烯表面的吸附机理.首先计算了各吸附体系的吸附能、净电荷转移量以及态密度,比较了羟基与羧基修饰石墨烯对GIS特征气体的吸附能力;再通过分子前线轨道与能隙对吸附能力强弱的机理进行了研究,得出强吸附修饰官能团的规律性特征,并通过氨基石墨烯进行验证.结果表明:羧基与羟基修饰石墨烯能够有效提高对SO_2,SOF_2,SO_2F_2的吸附能力,但羧基石墨烯对GIS特征气体的整体吸附能力更强;异性官能团修饰石墨烯后的能隙及其与气体分子前线轨道能量差越小,对GIS特征气体吸附能力就越强,异性官能团修饰石墨烯的能隙与前线轨道能量差可以作为选择特征气体敏感材料的依据.

DFT Study on Adsorption Abilities of Graphene Modified by Anisotropic Functional Groups to GIS Characteristic Gas

To develop a high sensitivity gas sensor for gas insulated switchgear (GIS), the adsorption process of GIS characteristic gas (SO2, SOF2, SO2F2, CF4) on the surface of graphene modified by hetero-functional groups (hydroxyl, carboxyl and amino groups) was simulated by molecular simulation software using density functional theory, the adsorption mechanism of GIS characteristic gas on the surface of heterogeneous functional group modified graphene was studied from the microscopic point of view. Firstly, the adsorption energy, net charge transfer and density of states of each adsorption system were calculated, and the adsorption capacity of hydroxyl and carboxyl modified graphene for GIS characteristic gas was compared; Then, the mechanism of the strong or weak adsorptive ability of the Molecular Frontier orbits and energy gaps was studied, and the regularity of the strong adsorptive modified functional groups was obtained, and the results were verified by amino graphene. The results show that: Carboxyl and hydroxyl modified graphene can effectively improve the adsorption capacity of SO2, SOF2 and SO2F2, but the overall adsorption capacity of carboxyl graphene for GIS characteristic gas is stronger. The smaller the energy gap of the anisotropic functional group modified grapheme and the frontier orbital energy difference between the anisotropic functional group modified graphene and the gas molecule, the stronger the ability to adsorb the characteristic gas of GIS. The energy gap and the frontier orbital energy difference of the anisotropic functional group modified graphene can be used as the basis for selecting the characteristic gas sensitive material.