Pd Loaded TiO₂ Nanotubes for the Effective Catalytic Reduction of p-Nitrophenol

Titania nanotubes decorated with Pd nanoparticles were synthesised by a hydrothermal method. The increased amounts of Pd concentration is found to facilitate the anatase to rutile crystalline phase transformation as well as in collapse of the morphology as revealed by X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopy. The presence of metallic as well as the oxidized form (PdO₂) of surface metal ions was characterized by using XPS. The catalytic activity of the Pd loaded titania nanotubes has been demonstrated by studying the reduction of p-nitrophenol to p-aminophenol. The 1.0 mol% Pd loaded titania nanotubes has been found to exhibit optimum catalytic activity (rate constant of 0.7072 min^-1) while those with higher amounts of Pd loading showed lower catalytic activity. It is observed that retention of tubular morphology and higher anatase content play significant roles in their catalytic activity.