Analysis of adsorption properties of SF6 decomposed gases (SOF2, SO2F2, SF4, CF4, and HF) on Fe-doped SWCNT: A DFT study

Abstract

In order to develop a potential material for monitoring of SF6 decomposed gases online in insulated equipment, the Fe-doped single-walled carbon nanotube (Fe-SWCNT) was proposed and its gas sensing properties to five SF6 decomposed gases were investigated with DFT method. The adsorption structures, charge transfers, density of states (DOS), and frontier molecular orbital theory analysis have been performed. Calculations show that the doping of Fe enhances the conductivity of SWCNT and Fe acts as the active center for adsorption. The conductivity of zigzag Fe-(8, 0) SWCNT is increased with SOF2 adsorption. While the adsorption of SF4 distinctly decreases the conductivity of the system. For SO2F2 adsorption, the difference in adsorption energy of different configurations is small, but the HOMO-LUMO energy gaps vary widely. The adsorption of SO2F2 is weaker than that of SOF2 and SF4. For adsorption of CF4 and HF, the little electron transfer and the low adsorption energy indicate the weak interaction. The negligible decreases of conductivity confirms that the Fe-(8, 0) SWCNT is insensitivity for CF4 and HF detection. After SO2F2, SF4, CF4, and HF adsorbed onto armchair Fe-(5, 5) SWCNT, the conductivity of system is also changed.