Adsorption of H, H2, and H2O inside and outside of (M@Si16F)6 tubelike aggregates and wires (MÂ =Â V, Ta). A first principles study

► Adsorption of H, H2, and H2O on porous materials assembled from V/Ta@Si16F units. ► van der Waals functional yields ∼3 times higher H2 adsorption energy than GGA one. ► The highest GGA-PBE absorption energy is ∼0.09 eV per H2 on (V@Si16F)6 aggregate. ► Dissociative adsorption of H2 is exothermic on the (V@Si16F)6 finite ring aggregate. ► Encapsulation of H2O is favored when its axis is not parallel to the tube axis.