A DFT study of SO2 and H2S gas adsorption on Au-doped single-walled carbon nanotubes

Intrinsic carbon nanotubes (CNTs) show limited toxic gas detection, thus, we need to develop a method to fabricate a novel CNT sensor that has good sensitivity. In this study, density functional theory (DFT) was applied to determine the adsorption behavior of Au-doped single-walled carbon nanotubes (Au-SWCNTs) to SO2 and H2S. The calculated results show that Au-SWCNTs have a high sensitivity to SO2 and H2S. When SO2 adsorbs on the surface of the nanotube, a large number of electrons transfer from the Au-SWCNT to SO2, which results in a decrease in the frontier orbital energy gap and an increase in electrical conductivity. On the other hand, when H2S adsorbs on the surface of the nanotube, the electrons transfer from H2S to the Au-SWCNT, the frontier orbital energy gap increases, and the electrical conductivity decreases. Thus, SO2 and H2S could be detected by Au-SWCNTs. This conclusion is useful for the development of CNT-based gas sensors and provides a theoretical basis to fabricate Au-SWCNT-based gas sensors.