Enhanced Photocatalytic Activity of Nitrogen-Doped Titania by Deposited with Gold

N-doped TiO2 deposited with Au (Au/N−TiO2) was successfully prepared via hydrolysis of titanium sulfate and ammonia followed with a Au deposition−precipitation method. The resulting samples were characterized by X-ray diffraction (XRD), atomic absorption flame emission spectroscopy (AAS), UV−vis absorbance spectroscopy, X-ray photoelectron spectroscopy (XPS), N2 physical adsorption, high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra. The photocatalytic activities of the samples were evaluated for degradation of methyl orange (MO) under visible light and UV light irradiation. It was found that the Au/N−TiO2 samples presented much higher photocatalytic activity than N-doped TiO2 under both UV and visible light irradiation. Diffuse reflectance UV−vis spectra showed an extension of light absorption into the visible region for Au/N−TiO2, and PL analysis of the sample indicated that the electron−hole recombination has been effectively inhibited after Au particles deposition. XPS analysis displayed Au existing as Au0 on the surface of the N−TiO2 photocatalyst and nitrogen species in the form of N−Ti−O and Ti−O−N. The excellent photoactivities of Au/N−TiO2 compared with N-doped TiO2 could be explained by its appropriate Au particle sizes and cooperation effect between N species and metallic Au particles.