Diffusion of single dye molecules in hydrated TiO 2 mesoporous films

ANGIOLINI, JUAN F.; STORTZ, MARTÍN; STEINBERG, PAULA Y.; MOCSKOS, ESTEBAN; BRUNO, LUCIANA; SOLER-ILLIA, GALO; ANGELOMÉ, PAULA C.; WOLOSIUK, ALEJANDRO; LEVI, VALERIA

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2017 vol. 19 p. 26540 - 26544

1463-9076

Mesoporous oxide films are attractive frameworks intechnological areas such as catalysis, sensors, environmentalprotection, and photovoltaics. Herein, we used fluorescencecorrelation spectroscopy to explore how the pore dimensions ofhydrated TiO2 mesoporous calcined films modulate the moleculardiffusion. Rhodamine B molecules in mesoporous films follow aFickian process 2-3 orders slower compared to the probe in water.The mobility increases with the pore and neck radii reaching anapproximately constant value for neck radius > 2.8 nm. However,the pore size does not control the dye diffusion at low ionicstrength emphasizing the relevance of the probe interactions withthe pore walls on the dye mobility. In conclusion, our results showthat the thermal conditioning of TiO2 mesoporous films providesan exceptional tool for controlling the pore and neck radii in thenanometer scale and has a major impact on molecular diffusionwithin the mesoporous network.