Photocatalytic activity under UV/Visible light range of Nb-doped titanate nanostructures synthesized with Nb oxide

Highlights: • Visible light responsive Nb-doped TiO₂ were synthesized by hydrothermal process. • Economical and stable Nb₂O₅ powder was used as niobium source. • The Nb-doped TiO₂ had a porous network structure. • The Nb-doped TiO₂ exhibited better photocatalytic activity than of pure TiO₂. - Abstract: In this work, using economical and stable niobium oxide (Nb₂O₅) powder as niobium source, visible light responsive Nb-doped titanate nanostructures were synthesized by hydrothermal process. The synthesized Nb-doped titanate nanostructures were composed of two types of titanate nanostructures (nanotubes and nanosheets) and TiO₂ nanoparticles. They have a smaller band gap energy of 3.24 eV compared to pure TNTs that were synthesized under the same experimental conditions. The photocatalytic activity of the synthesized Nb-doped titanate nanostructures was evaluated under visible light irradiation through the degradation of methylene blue (MB) and rhodamine B (RhB). Consequently, the synthesized Nb-doped titanate nanostructures exhibited much higher photocatalytic activity under visible light irradiation than pure TNTs. The photocatalytic activity of the synthesized Nb-doped titanate nanostructures was 1.4 times (MB) and 3.1 times (RhB) higher than of pure TNTs because the Nb-doping narrowed the band gap and it accelerated the separation of photo-induced electron-hole pairs.