Graphene/hexagonal boron nitride heterostructure: A promising material for ammonia gas sensing devices in humid environments

Abstract Elucidating the co‐adsorption mechanism of H 2 O and NH 3 onto graphene/hexagonal boron nitride heterostructures (h‐BN) is critical to guide the design of new materials for application in ammonia gas sensor devices in humid environments. Here, we use first principles methods with non‐empirical van der Waals density functional theory to investigate the adsorption of graphene/h‐BN to NH 3 + H 2 O. Our results show that the presence of water vapor enhances the sensitivity and the thermodynamical stability of the ammonia + graphene/h‐BN through the formation of NH 3 •H 2 O clusters adsorbed directly on the graphene/h‐BN. The presence of water vapor leads to the decrease of the adsorption energy to −0.613 eV, much more negative than that for the adsorption of NH 3 gas, and the increasing of the electron transfer from the adsorbates to graphene/h‐BN heterostructure, more twice larger than that for the adsorption of solely ammonia. Additionally, the recovery time of graphene/h‐BN for the co‐adsorption of NH 3 + H 2 O is predicted to be quite short, in seconds range, in good agreement with experiment work. The results demonstrate the potential for application of graphene/h‐BN for ammonia gas sensors with high performance and mechanical stability in humid environments.