Influence of Preparation Methodology on the Photocatalytic Activity of Nitrogen Doped Titanate and TiO2 Nanotubes.

Titanate and TiO2 nanotubes (TiNTs and TiO2NTs) are known as good photocatalysts under UV light irradiation, due to their high band gap energy. The nitrogen-doping process is one of the most studied methods to make these materials sensitive to visible light. However, most of these studies are focused on how calcination temperature affects the crystalline structure and, consequently, the photocatalytic efficiency, and few are investigated about the choice of the doping method. Here we report the synthesis of nitrogen-doped TiNTs and TiO2NTs (NTiNTs and NTiO2NT) through two different methods, and the comparison of the obtained materials properties. The photocatalytic efficiency was evaluated under visible light and correlated to the nature of nitrogen doping, which is a consequence of the doping method chosen. We found that the NTiNT's lamellar structure and its more negative zeta potential shall facilitate its interaction with the dye to be degraded. Moreover, the adsorbed nitrogen plays an important role over the degradation process.