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

The adsorption of water vapor in mesoporous TiO<sub>2</sub> was studied by nuclear magnetic resonance (NMR) and multiscale molecular dynamics simulations. Three different water environments 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; and a bulk-like fraction of mobile water. The obtained NMR results can be explained in the framework of molecular dynamics simulations that give insight on the filling mechanisms in TiO<sub>2</sub> nanoporous materials. For these highly hydrophilic materials, it is shown that adsorption isotherms may render a smaller effective pore size due to the presence of a layer of highly bound water. The synergistic combination of experimental NMR data and MD simulations renders a detailed analysis of the water dynamics inside the titania pore space.