Nanostructured Pure Anatase Titania Tubes Replicated from Electrospun Polymer Fiber Templates by Atomic Layer Deposition

Abstract

Pure anatase TiO2 submicrotubes were successfully fabricated by a template-directed method. Electrospun poly(vinyl pyrrolidone) (PVP) fibers were used as a soft template for coating with titanium dioxide using an atomic layer deposition (ALD) technique. The deposition was conducted onto a template at 70 °C by using titanium tetraisopropyl oxide (TIP) [Ti(OiPr)4] and pure water as precursors of TiO2. Crystalline structure, microstructure, and optical properties of the TiO2 deposited layers before and after calcination were studied in detail. While the as-deposited TiO2 layers onto ES fibers were completely amorphous with thickness of about 60 nm, the TiO2 layers after calcination at 500 °C for 4 h were properly converted into polycrystalline nanostructured TiO2 submicrotubes with high quality of anatase. Thereby, the optical band gap energy was also tuned with a blue shift. As final products the self-supported free-standing mats consisting of pure anatase TiO2 submicrotubes can be easily handled and reclaimed for use in future applications related to catalysis, electronics, photonics, sensing, medicine, and controlled drug release