Polishing effect on anodic titania nanotube formation

Titania nanotubes represent exciting opportunities in solar cell, sensing, and catalytic applications. In this work, four different surface polishing conditions: as-received, chemical polishing, mechanical polishing, and electropolishing, are studied in order to understand the effect of different surface conditions on the anodization process and nanotube morphology. At the same anodization condition of 100 V in 0.1 M NH4F ethylene glycol at 0 °C for 3 min, the as-received and mechanically polished samples show nano-tubular surfaces while the chemically polished and electropolished samples have oxide layers on the top of the nanotubes. The nanotube morphologies, anodization current vs. time curves, and the bottom barrier layers are all related to the Ti surface conditions. The electropolished surface leads to the most homogeneous TiO2 nanotube formation.

► Four different surface polishing conditions are studied in order to understand the effect of different surface conditions on the anodization process and nanotube morphology. ► The nanotube morphologies, anodization current vs. time curves, and the bottom barrier layers are all related to the Ti surface conditions. ► The as-received and chemically polished samples have rough surfaces and the corresponding nanotube morphologies and the bottom oxide barrier layer are nonuniform. ► The mechanically polished sample has a flat nanotube oxide barrier layer but the nanotube size is non-uniform. ► The electropolished sample has flat polished surface; the nanotubes show the most uniform sizes and round shapes and are desired for Ti anodization.