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.