Diffusion of single dye molecules in hydrated TiO2 mesoporous filmsElectronic supplementary information (ESI) available: Experimental details of MOTF synthesis and characterization techniques: transmission electron microscopy, 2D small-angle X-ray scattering, FTIR spectroscopy, environmental ellipsometric porosimetry and X-ray diffraction. See DOI: 10.1039/c7cp05186g

• Main Authors: Angiolini, Juan F, Stortz, Martín, Steinberg, Paula Y, Mocskos, Esteban, Bruno, Luciana, Soler-Illia, Galo, Angelomé, Paula C, Wolosiuk, Alejandro, Levi, Valeria
• Format: Journal Article
• Language: English
• Published: 11.10.2017
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c7cp05186g

Mesoporous oxide films are attractive frameworks in technological areas such as catalysis, sensing, environmental protection, and photovoltaics. Herein, we used fluorescence correlation spectroscopy to explore how the pore dimensions of hydrated TiO 2 mesoporous calcined films modulate the molecular diffusion. 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 a neck radius >2.8 nm. However, the pore size does not control the dye diffusion at low ionic strength emphasizing the relevance of the probe interactions with the pore walls on dye mobility. In conclusion, our results show that the thermal conditioning of TiO 2 mesoporous films provides an exceptional tool for controlling the pore and neck radii on the nanometer scale and has a major impact on molecular diffusion within the mesoporous network. Fluorescence correlation spectroscopy (FCS) shows how the pore dimensions of thin and hydrated TiO 2 mesoporous calcined films modulate the diffusion of molecules across the pore network.