Boron substituted graphene: energy landscape for hydrogen adsorption

We have analyzed the modifications of interaction energy between a molecule of hydrogen and graphene layers partially substituted by boron. We show that the presence of boron modifies the symmetry of the energy landscape. It is due to both the larger boron size (with respect to carbon) and its stronger interaction with hydrogen molecules. The changes of energy surface are not confined to the neighborhood of substituted sites but extend over several graphene carbon sites, making the surface more heterogeneous. We show that the average increase of adsorption energy could meet DOE targets for hydrogen storage if a partial charge transfer between boron and hydrogen occurs during adsorption.