First-principles study of cobalt silicide nanosheet and nanotubes: Stability and electronic properties

We perform first-principle calculations to study the geometric and electronic structures of cobalt silicide (CoSi₂) nanosheet and nanotubes. The structure of layered CoSi₂ is characterized by a CoSi₂ nanosheet, analogous to the (1 1 1) surface of CoSi₂ crystal. The strain energy involved in rolling up a CoSi₂ nanosheet to CoSi₂ nanotubes is very low. Both the CoSi₂ nanosheet and nanotubes are energetically stable. CoSi₂ nanotubes prefer to form bundles to further release strain energy. All CoSi₂ nanotubes exhibit uniformly metallicity and steady work functions, independent of tube chirality.