Adsorption of gases from SF6 decomposition on aluminum-doped SWCNTs: a density functional theory study

Abstract

Adsorption of gases produced by SF6 decomposition (i.e., SO2, H2S, SOF2, SO2F2, and CF4) by aluminum-doped zigzag (8, 0) single-walled carbon nanotubes (Al-SWCNTs) was investigated based on first-principles density functional theory (DFT). Different binding sites were considered to determine the most stable structures. Furthermore, adsorption energy, density of state, band structure, frontier molecular orbital, and population were analyzed to interpret the mechanism of gas adsorption on the surface of Al-SWCNTs. The calculation results predicted that the Al atom acted as an active site to adsorb the SF6 decomposition products in the adsorption process. SO2, H2S, and CF4 molecules were adsorbed on the sidewall of Al-SWCNTs by physisorption, whereas SOF2 and SO2F2 were molecularly chemisorbed. Conductivity of Al-SWCNTs was increased when the gas molecules of SO2, H2S, and SO2F2 were adsorbed. Conversely, SOF2 adsorption slightly decreased the conductivity of the adsorption system. Al-SWCNTs were insensitive to CF4. The different responses in conductivity of Al-SWCNTs for different gas molecule adsorptions present a potential selective and sensitive gas detection sensor.