Influence of Pt and Pd Modification on the Visible Light Photocatalytic Activity of N-Doped Titania Photocatalysts

Pd and Pt modified N-doped titania nanoparticle powders were prepared by a facile sol-gel method. Nitrogen doping and metal modification were carried out simultaneously during the preparation process. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and X-ray photoelectron spectroscopy (XPS). The visible light photocatalytic activities of the as-prepared samples were evaluated by analyzing their effect on the photocatalytic decomposition of methyl orange (MO). The chemical state of the metal is the key factor determining the performance of metal modified N-doped titania. The Pd used to modify the N-doped titania (Pd-NT) in our study was of the PdOx(x <= 2) species, which increased the absorbance in the visible light region, decreased the recombination of photo-generated electron-hole pairs, and resulted in a significant enhancement in the visible light photocatalytic activity. The Pt species used to modify the N-doped titania (Pt-NT) was mainly in the metallic state, which resulted in a decrease in the absorbance in the visible light region, and an increase in the recombination of photo-generated electron-hole pairs. Pt modification led to a deterioration in the visible light photocatalytic activity of the material.