Preparation of Pd-loaded La-doped TiO₂ nanotubes and investigation of their photocatalytic activity under visible light

Orthorhombic titanic acid nanotubes (TAN) have large BET surface area and small-diameter one-dimensional nanotubular morphology, so they can work as a good supporter and a precursor of TiO₂. However, in our former research, we found that calcination of TAN to anatase TiO₂ would destroy the nanotubular structure and decrease the BET surface area sharply. In this work, we utilized the pillar effect of the foreign nanoparticles (La₂O₃) to keep the nanotubular morphology of TiO₂, and obtained the anatase TiO₂ nanotubes with large BET surface area. For improving the photocatalytic activity, Pd nanoparticles were loaded as the electron traps on the surface of La-doped TiO₂ by photo-deposition method. The photocatalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, diffuse reflectance spectra, and N₂ adsorption–desorption isotherms measurement. Their photocatalytic activities were evaluated by the removal of propylene under visible light irradiation (λ ≥ 420 nm). The results showed that the photocatalytic activity of Pd-loaded La-doped TiO₂ nanotubes improved effectively compared with that of La-doped TiO₂ and pure TiO₂.