Diffusion of single dye molecules in hydrated TiO 2 mesoporous films

ANGIOLINI, JUAN FRANCISCO; MOCSKOS, ESTEBAN; ANGELOMÉ, PAULA C.; STORTZ, MARTIN; SOLER-ILLIA, GALO JUAN DE AVILA ARTURO; LEVI, VALERIA; STEINBERG, PAULA YAEL; BRUNO, LUCIANA; WOLOSIUK, ALEJANDRO

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

ROYAL SOC CHEMISTRY

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

1463-9076

Mesoporous oxide films are attractive frameworks in technological areas such as catalysis, sensors, environmental protection, and photovoltaics. Herein, we used fluorescence correlation spectroscopy to explore how the pore dimensions ofhydrated TiO2 mesoporous calcined films modulate the moleculardiffusion. Rhodamine B molecules in mesoporous films follow a Fickian process 2-3 orders slower compared to the probe in water. The mobility increases with the pore and neck radii reaching an approximately 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 with the pore walls on the dye mobility. In conclusion, our results show that the thermal conditioning of TiO2 mesoporous films provides an exceptional tool for controlling the pore and neck radii in the nanometer scale and has a major impact on molecular diffusion within the mesoporous network.