Controlling cross section of carbon nanotubes via selective hydrogenation

We systematically studied effects of selective hydrogenation of single-walled carbon nanotube (SWNT) on the shape of tube cross section based on a mechanical relaxation model and ab initio calculations. We found that fully hydrogenated SWNTs (FH-SWNTs) are energetically more favorable than partially hydrogenated ones. We uncovered a new channel for the strain relaxation at the nanoscale, in contrast to the known plasticity or buckling channel. We showed that the curvature strain energy of a cylindrical FH-SWNT can be significantly relieved by flipping a few rows of H atoms from outside to inside of the tube. We conclude that selective hydrogenation of SWNTs not only can be an effective way to achieve highly stable configurations of FH-SWNTs but also can be used to control the shape of tube cross section (triangle, square, etc.) for nanomechanic applications.