Effect of oxygen on single-wall silicon carbide nanotubes studied by first-principles calculations

摘要

According to the predictions of first-principles calculations, single-wall silicon carbide nanotubes exhibit several unusual properties: they are semiconducting independently of their chirality, superior material for hydrogen storage, and have strong nonlinear optical coefficients. Nevertheless, only a single experiment indicates, in our knowledge, that a tubular form of silicon carbide (SiC) exists. It is known that the surface of bulk silicon carbide is oxidized in the presence of oxygen; therefore, oxygen may destabilize its tubular form. We applied ab initio density-functional theory calculations to investigate this important issue. We found that (ⅰ) the structure of silicon carbide nanotubes remain intact in ambient oxygen, (ⅱ) but the oxygen molecule dissociates as interstitials on silicon carbide nanotubes even at room temperature, and (ⅲ) the interstitial oxygen is a fast diffuser on SiC nanotubes.