Theoretical Investigation of Rhodium-Decorated Gallium Nitride Nanotubes for Sulfur Hexafluoride Decomposition Products Sensing and Scavenging Applications.

Gas-insulated switchgear (GIS) plays an important role as a modern power distribution device in power plants and power stations, which is commonly filled with SF₆ insulating gas. During the equipment operation, the inevitable partial discharge causes SF₆ to be broken down into gas (SF₄, SOF₂, SO₂, and H₂S), which degrades the insulation performance of the GIS. This paper is devoted to the detection of partial discharge and the removal of SF₄ and SOF₂, which are not conducive to insulation, by exploring new gas-sensing materials for characteristic gas detection. Based on first-principles calculation, on the one hand, the most stable adsorption configurations of rhodium-decorated gallium nitride nanotubes (Rh-GaNNTs) and gas adsorption systems were obtained. On the other hand, the doping and adsorption mechanisms were analyzed by band structure, density of states, deformation charge density, and molecular orbital theory. Subsequently, the gas-sensitive performance of Rh-GaNNTs for these four impurity gases was evaluated by analyzing the sensing response and recovery time. The adsorption stability and recovery time of Rh-GaNNTs to these gases are ranked as SF₄ > SOF₂ > SO₂ > H₂S; the order of influence of gas adsorption on sensitivity response is H₂S > SO₂ > SF₄ ≈ SOF₂. Calculation results show the potential of Rh-doped surfaces as reusable H₂S and SO₂ sensors and suggest their use as gas scavengers to remove SF₄ and SOF₂, especially SOF₂.