First-principles design of well-ordered silica nanotubes from silica monolayers and nanorings

The structural characters and the possible synthetic routes of the hypothetical silica nanotubes (NTs) have been explored by using first-principles calculations. Silica nanorings (NRs) based on linked three-membered rings (3MRs) and silica monolayers (MLs) consisting of hybrid two- and six-membered rings (2-6MRs) or pure four-membered rings (4MRs) are presented as promising precursors for the fabrication of well-ordered silica NTs. Three kinds of silica NTs, namely, 2-3MR-NTs, 2-6MR-NTs, and 4MR-NTs, built from NRs and MLs are predicted to have lower strain energies than the edge-sharing silica fiber, among which the 4MR-NTs are energetically most favorable. The electronic structures of these silica nanomaterials are also discussed to promote the potential applications in nanoscience and nanotechnology.