Simulation study of hydrogen storage in two kinds of Y-junction carbon nanotubes

The physisorption and chemisorption of hydrogen on two types of Y-junction carbon nanotubes(Y-(6,6) and Y(10,0)) have been studied using molecular dynamics (MD) simulations and semiempirical (AM1) method. The MD simulations study show that H₂ molecule can penetrate into the open ends of the branches and stay inside even at room temperature, which is confirmed by the study of potential energies for different pathways with AM1 method. Furthermore, the potential energy variation of H₂ penetrating into the open end along the axis of one branch arm is quite similar to that of H₂ in straight carbon nanotubes. The study of chemisorption of hydrogen atoms on Y (6,6) indicates that the carbon atoms in the heptagons are more active to bind hydrogen atoms. It has been also found that the neighboring carbon atoms of Y (6,6) prefer to bind two hydrogen atoms.