Theoretical Study of the Gas Sensing Mechanism of N3&Ni Doped Double Vacancies Defect Graphene Upon SF6 Decompositions

It is an important way by detecting SF₆ decomposition products to evaluate the insulation condition of SF₆ insulated power equipment. In this paper, N₃&Ni doped 555-777graphene (N₃&Ni-graphene) is proposed as a new gas sensor to detect the characteristic components of SF₆ decomposition products: H₂S, SO₂, SOF₂ and SO₂F₂. In order to get insights into the gas sensing mechanism, the geometry structures, electron structures and conductivity are analyzed by simulation method based on density functional theory. The calculation results show that N₃&Ni dopant can improve the conductivity and surface activity of 555-777 graphene. Specifically, H₂S and SO₂ absorbing on N₃&Ni-graphene surface will increase the conductivity obviously, while the other two kinds of gas molecules will decrease the conductivity. The sensitivity of H₂S is greater than SO₂ according to the changed value of energy gap. It is also indicated that N₃&Ni-graphene can absorb the above four characteristic components stably with high adsorption energies, complex orbital hybridizations and multi-level charge transfer. This work will provide some theoretical guidance to develop a novel gas sensor to evaluate the insulation condition of SF₆ insulated equipment.