Graphene Structure Modification under Tritium Exposure: ³ H Chemisorption Dominates over Defect Formation by β ^– Radiation

Potential structural modifications of graphene exposed to gaseous tritium are important for membrane-based hydrogen isotope separation. Previously, it has been reported that tritium–graphene interactions cause absorption as well as vacancy defects in graphene. In this work, we investigate the mechanism, which leads to the generation of the vacancy defects. We find that such modifications cannot be explained by electron irradiation alone. Instead, the tritium radicals remaining after the decay are the primary cause of the modification of the graphene surface, as confirmed by confocal Raman microscopy. The effect of the interaction of tritium atoms with the graphene surface exceeds that of electron irradiation at the average energy of the beta particles (5.7 keV). Compared to other studies, which investigated high electron doses in the absence of tritium, remarkably low concentrations of tritium already induce a significant amount of defects at short exposure times. Our findings are supported by molecular dynamics simulations of graphene bombardment with tritium atoms. As a consequence, tritium saturation of graphene may alter its permeability for hydrogen isotopes, thus affecting potential applications.