The interaction between graphene-based materials and hydrogen isotopes is of great importance with respect to the adsorption of hydrogen in graphene and the removal of tritium from irradiated nuclear graphite. In the present study, based on density functional theory, we investigate and discuss the adsorption and molecular desorption of hydrogen isotopes on the edges and stable interior defects. The adsorption energy of one hydrogen on graphene-based materials is between -2.0 and -5.0 eV, which is related to the structure and hydrogenation level. The hydrogenation level increases with the hydrogen partial pressure and decreases with the temperature. The best adsorption pathways of hydrogen isotopes in graphene-based materials are determined, together with three different desorption stages with different activation energies. The desorption peaks of thermal desorption spectrometry agree well with stage 2 and stage 3 of simulation. Our results can provide a theoretical basis for the study of the hydrogen isotope behaviors in graphene and the decontamination of nuclear graphite.
© 2021 The Authors. Published by American Chemical Society.