Metal-assisted hydrogen storage in nanostructured carbons

First-principle calculations at ORNL on interactions between hydrogen and graphite provided the fundamental basis for experimental work on metal-doped, activated carbon fibers (produced at Clemson). Measurements at ORNL revealed that the Pd doped fibers exhibited a hydrogen storage capacity of about 2 wt% at ambient temperature and a pressure of 2 MPa. This represented an order of magnitude improvement over the capacity of the corresponding Pd free fibers. Further modeling work indicated that, provided the high energy barrier for initial sorption could be overcome, hydrogen could be stored by intercalation between graphene layers. On the basis of these preliminary findings, it is hypothesized that metal assisted hydrogen storage in nanostmctured carbon is the result of catalytic activation of molecular H2 and surface diffusion of H atoms, followed by storage on carbon structural defects through either chemical bonding or intercalation. We will present both modeling and experimental results.