Novel Chemical Sensor for CO and NO: Silicon Nanotube

Using the first-principles calculation, we investigate the adsorption of CO and NO on (8, 0) silicon nanotubes (SiNTs). The detailed analysis of the structural and electronical properties of various optimized configurations is performed. The results show that CO molecule can be chemisorbed on SiNT with the C atom bonding with the Si atom of the tubular surface when CO is located on the top site, accompanying with the binding energy of 1.559 eV and charge transfer of 0.658 vertical bar e vertical bar, which are larger than the results of other configurations. For the SiNT-NO systems, there exist four strong chemical adsorption configurations. The most stable configuration is the N atom bonding with two Si atoms on the bridge site. The binding energy is 2.135 eV and charge transfer is 2.064 vertical bar e vertical bar. In addition, it is found that both the C-O and N-O bonds are elongated when CO and NO are chemisorbed on SiNT. Compared to carbon nanotubes (CNTs) or silicon carbon nanotubes (SiCNTs), the SiNTs have stronger interaction with the CO and NO and can provide more sensitive signal for CO and NO sensing. In particular, the semiconducting (16, 0) SiNT would become metallic after adsorption CO, and the SiNTs after adsorption of NO would be magnetic, which can serve as a sensitive signal for CO or NO sensing. In short, the SiNTs with the semconducting structure are a very promising candidate for CO and NO sensing and detection.