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. (authors)