Recombination and Exchange Reactions of Hydrogen and Dihydrogen Molecular Condensation in Single-Walled Carbon Nanotubes

Abstract

The hydrogen recombination reaction, H + H → H2, and the hydrogen exchange reaction, H + H2→ H2 + H, taking place inside single-walled carbon nanotubes have been studied by using quantum mechanics molecular dynamics simulations. Two types of hydrogen exchange reactions have been found. The fast reaction lasts in less than 5 fs, and the slow one lasts for about 40 fs with a clear intermediate state manifested. The collisional reaction for two H atoms to form a H2 molecule usually takes place in a time interval of 25 fs. We also describe the detailed process of the reaction of individual H atoms to form H2 molecules and, with an increase of the density of H2 molecules confined in the tubes, H2 molecular condensation to form clusters and finally to form condensed H2 molecular lattices.