Structure and mobility of water confined in AlPO-54 nanotubes.

We performed molecular dynamics simulations of water confined within AlPO-54 nanotubes. AlPO-54 is an artificial material made of AlO and of PO in tetrahedra arranged in a periodic structure forming pores of approximately 1.3 nm in diameter. This makes AlPO-54 an excellent candidate for practical applications, such as for water filtration and desalination. In this work, the structural and dynamical properties of the confined water are analyzed for various temperatures and water loadings. We find that the water structure is controlled by the heterogeneity of the nanopore surface with the water molecules located preferentially next to the surface of oxygens of AlPO-54; consequently, at very low densities, water forms helicoidal structures in string-like arrangements.