Theoretical studies of chemisorption of NO2 molecules on SiC nanotube

Silicon carbide (SiC) nanotubes have attracted extensive attention due to the unique properties. Modifying the electronic properties of SiC nanotubes is helpful for further widening their potential applications. In this paper, we have studied the chemisorption of NO2 molecules at different coverage on a series of SiC nanotubes through density functional theory (DFT) calculations. The results indicate that changes in energetic, structural and electronic properties of the SiC nanotubes are significantly dependent on the coverage of adsorbed NO2 molecules: (1) a nitrite-like structure is obtained for an odd number of NO2 molecules adsorption on the SiC nanotube, while an even number of NO2 molecules adsorption leads to a nitro-like configuration; (2) the adsorption energy per NO2 molecule for even number adsorption is larger than that of odd number, suggesting that the NO2 groups prefer the pair arrangement due to the coupling of two radicals; (3) with the increase of the coverage of the adsorbed NO2, the band-gaps of SiC nanotubes are decreased, thus leading to the enhancement of the electro-conductivity of SiC nanotubes. Our results might provide an alternative strategy to modify the properties of SiC nanotubes, which might be useful for the design of SiC nanotubes-based nanodevices.