Water Confined in Mesoporous TiO 2 Aerosols: Insights from NMR Experiments and Molecular Dynamics Simulations

Abstract

The adsorption of water vapor in mesoporousTiO2 was studied by nuclear magnetic resonance (NMR) andmultiscale molecular dynamics simulations. Three different waterenvironments were distinguished and quantified: a first layer,where strongly bound water molecules exist at the inner surfaces;a second less structured layer but still with restricted mobility; anda bulk-like fraction of mobile water. The obtained NMR resultscan be explained in the framework of molecular dynamicssimulations that give insight on the filling mechanisms in TiO2nanoporous materials. For these highly hydrophilic materials, it isshown that adsorption isotherms may render a smaller effectivepore size due to the presence of a layer of highly bound water.The synergistic combination of experimental NMR data and MDsimulations renders a detailed