Water confinement in hierarchical porous silica and titania

Abstract

Here, water confinement in hierarchical porous silica and titania has been investigated by NMR relaxometry techniques. Results show a greater interaction of water with the TiO2 surface than with the SiO2 one. However, whatever the matrix, no effect of the porosity is noted on the water relaxion. For the silica-based materials, two regimes are observed. The first one at low frequency corresponds to a surface diffusion phenomenon and the second one at high frequency is due to the motion of molecules located in a layer of water further from the surface. Concerning mesostructured titania water relaxation is governed by very slow surface diffusion.