Behavior of H2O molecule in carbon nanotube/boron nitride nanotube heterostructure

We perform total-energy electronic-structure calculations of a water molecule inside a (7, 7) carbon nanotube/boron nitride nanotube (CNT/BNNT) heterojunction. The van der Waals interaction is also considered in this study. We find that the equilibrium distance between the water molecule and the wall of the CNT (BNNT) is ≈ 3.3 Å, and the encapsulation energy is 0.22 eV (0.25 eV). The energy profile along the tube axis exhibits a dramatic change in the vicinity of the heterojunction. A speed change of water flow is expected to occur near the heterojunction. Such information would provide valuable insight in nanostructure design for nanofluidics. [Display omitted] •We study the behavoir of a single H2O molecule in a CNT/BNNT heterstrcuture using first-principles calculations.•The H2O molecule has slightly higher encapsulation energy inside the BNNT than inside the CNT.•A dramatic change in flow speed of the H2O molecule may occur near the heterojunction.•The findings have implications for the field of nanofluidics and the future development of H2O purification technology.