Using spin-polarized density functional theory, an investigation was made of the incorporation of H adatoms on antisites and vacancies present in zig-zag (10,0) and in armchair (6,6) nanotubes. It was found that the presence of antisites, SiC and CSi, increased the incorporation rate of H adatoms, giving rise to monohydrogenated HSiC and HC-CSi configurations. In the former structure, the H adatom bonded to the SiC antisite, whereas in the latter the H adatom bonded to the C atom nearest neighbor to the CSi antisite. Increasing the coverage of H adatoms, two H adatoms, the binding-energy results indicated that the H adsorption on the neighboring Si and C sites represented the energetically most stable configuration. For C vacancies, binding energies of −2.8 and −3.2eV/H atom were obtained for monohydrogenated and dihydrogenated Si dangling bonds, respectively. Those values of binding energies indicated that the H adsorption on C vacancies was exothermic process when compared with the binding energy of an isolated H2 molecule. For both nanotube chiralities, monohydrogenated Si vacancies represent the energetically most favorable configuration.

Hydrogen Interaction with Native Defects in SiC Nanotubes. R.J.Baierle, R.H.Miwa: Physical Review B, 2007, 76[20], 205410