Band engineering of double-wall Mo-based hybrid nanotubes

Hybrid transition-metal dichalcogenides (TMDs) with different chalcogens on each side (X-TM-Y) have attracted attention because of their unique properties. Nanotubes based on hybrid TMD materials have advantages in flexibility over conventional TMD nanotubes. Here we predict the wide band gap tunability of hybrid TMD double-wall nanotubes (DWNTs) from metal to semiconductor. Using density-function theory (DFT) with HSE06 hybrid functional, we find that the electronic property of X-Mo-Y DWNTs (X = O and S, inside a tube; Y = S and Se, outside a tube) depends both on electronegativity difference and diameter difference. If there is no difference in electron negativity between inner atoms (X) of outer tube and outer atoms (Y) of inner tube, the band gap of DWNTs is the same as that of the inner one. If there is a significant electronegativity difference, the electronic property of the DWNTs ranges from metallic to semiconducting, depending on the diameter differences.