Potassium influence in the adsorption of hydrogen on graphene: A density functional theory study

The influence of potassium (K) on the hydrogen (H) adsorption on graphene (G) was studied by means of density functional theory with the generalized gradient approximation. The structural parameters, bonding and magnetic properties of one and two H atoms interacting with potassium doped graphene (H–K/G and 2H–K/G) are calculated for different energetically stable configurations. We found a charge transfer from K atom towards G even when the H atom pairs are adsorbed. This behavior is obtained for all the configurations studied here. The binding energy per H atom is greater in the most stable 2H–K/G arrangement than in both H–K/G and H/G systems. The present results suggest that the hydrogen atom binding energy on graphene layer could increase up to 82% due to the pre-adsorption of potassium.