One step synthesis of niobium doped titania nanotube arrays to form (N,Nb) co-doped TiO ₂ with high visible light photoelectrochemical activity

The chemical modification of aligned titanium dioxide nanotube (TiO2-NT) arrays provides new doping possibilities to improve their photoelectrochemical activity under visible light. Niobium doped TiO2-NTs containing up to 15% of Nb in the near-surface region are prepared by a flexible single step procedure using a fluoroniobate complex simultaneously acting as a source of the doping element and fluoride anions required for nanotube formation. This negatively charged complex allows an efficient insertion of Nb in the forming TiO2-NT structure during the anodization process. These nanotube arrays are further modified with nitrogen to achieve (Nb,N) co-doped nanotubes with noticeable visible light photoelectrochemical activity.