Mesoporous titania thin films with pseudo-cubic structure: Synthetic studies and applications to nanomembranes and nanotemplates

Abstract

By using the nanoparticle route, we have synthesized mesoporous titania thin films with interconnected pores in 3D. The pore size is approximately 3 nm and the pores form a pseudo-cubic structure derived from the Pm 3 ¯ m structure. By systematically studying the influence of the synthesis parameters such as the humidity during the spin-coating and aging steps, composition, aging temperature, and aging time, we have established optimal conditions for reproducible synthesis of pseudo-cubic structured mesoporous titania thin films. In addition to the conventional transmission electron microscopy and X-ray diffraction, the films were studied by atomic force microscopy, which revealed that the pore ordering of the films was highly regular without any defect in the scale of several hundred nanometers and the film surface was very flat and smooth with roughness less than 0.3 nm. Electrochemical analyses of several analyte molecules of different sizes on Pt electrodes with and without the mesoporous titania film coating clearly show that the mesoporous titania thin films have size exclusion properties in the nanometer scale. Using these titania thin films as a template, we have synthesized an array of nanoparticles of Ag that are interconnected to form a 3 D network within the pores by electrochemical deposition in aqueous solutions.