Insights on Ag doped porous TiO2 nanostructures: a comprehensive study of their structural and morphological characteristics

A comprehensive analysis of heterogeneous nanostructures based on TiO2 aerogels and Ag nanoparticles (NPs) is reported herein. The experimental techniques engaged along this study enable a multi-scale approach for the characterization of this composite system. The results clearly indicate that an increase of the Ag amount within the porous structure of TiO2 nanograins leads to a lower dispersion of Ag on the support. For a higher Ag global amount, the proportion of encapsulated NPs increases considerably, reducing in this manner the amount of accessible Ag. The effect of the thermal treatment on such nanostructures has been evaluated as well. The specimen annealing appears to induce a considerable diminution of the microporosity, finding that is in good agreement with the results obtained by measurement of the specific surface area of the TiO2 grains. The annealing also changes the microstructural characteristics of these nanostructures, as expected. More specific, it leads to an enhanced degree of encapsulation of Ag NPs, which as consequence become considerably less accessible. Being focused on the analysis of porous nanocomposites with specific properties, the current investigation aims as well at emphasizing the remarkable potential of electron tomography, a technique that can be successfully employed for precise analysis of three dimensional nanostructures.