Use of modified anodization procedures to prepare advanced TiO2 nanostructured catalytic electrodes and thin film materials

The preparation and characteristics of (i) thin films based on an ordered array of TiO2nanotubes (NT)supported on flexible Ti metallic substrate, (ii) free-standing TiO2NT thin films and (iii) hedgehog-typeTiO2 thin films are investigated. It is evidenced the possibility of a fine tuning of the nano-architecture inrelation to applications going from advanced catalytic (photo)electrodes to nanomembranes requiringdifferent nanostructure for an optimized behavior. In the first type of materials, a key issue determining the resistance to electron transfer and performances is the interface between the TiO2NT layer and themetallic substrate. Some aspects of the preparation in controlling nanomorphology and photocurrent generation properties are discussed. In free-standing TiO2NT thin films the mechanism of formationof flow-through nanomembranes is analyzed. The possibility of generation of hedgehog-type TiO2 thin films by etching with HF is also shown, evidencing some of the potential advantage of these catalytic materials, particularly for self-cleaning properties.