Hydrogen Storage in Silicon Carbide Nanotubes by Lithium Doping

Using ab initio density-functional theory, we have studied the interaction of hydrogen molecules (H-2) with a single lithium (Li)-doped silicon carbide nanotube (SiCNT). The hydrogen molecule physisorbs on a pure SiCNT with a binding energy of about 0.086 eV. However, the binding energy rises to 0.211 eV when H-2 binds to a Li-adsorbed SiCNT. The increase in binding is due to the charge transfer from Li to the nanotube. Up to four Hy molecules can be attached to a Li-adsorbed SiCNT with an average binding energy of 0.165 eV, which is close to the lowest requirement proposed by the U.S. Department of Energy, and it indicates that this system is a good storage medium for Hy.