Electric field induced silicon carbide nanotubes: a promising gas sensor for detecting SO2

Finding an effective strategy for detecting SO2 gas is very important in order to solve the problem of pollution of SO2. Based on the first-principles density functional theory (DFT) calculations, we herein explore the possibility of using (5, 5) silicon carbide nanotubes (SiCNTs) with an external electric field (EF) as a potential gas sensor for SO2 detection. It is found that SO2 molecules can be chemisorbed to the Si-C bonds of SiCNTs and can generate a different charge distribution under the EF, resulting in the breaking of some S-C bonds. It is these broken S-C bonds that induce a decrease in the band gap. Furthermore, with the concentration of SO2 exceeding 20%, the band gap of SiCNT under an EF of 9.00 V nm(-1) would be reduced from 1.75 eV for SiCNT to zero, indicating the transformation from a semiconductor to a conductor. Hence, with an appropriate EF, SiCNTs can effectively respond to SO2 and serve as sensors for detecting SO2 gas.