Doping titanium(IV) oxide(TiO2) with phosphorus (P) having negative charges was attempted in order to obtain P-doped TiO2 with a red shift of the absorption edge and visible-light photocatalytic activity. P-doped TiO2 was synthesized through the hydrolysis of titanium tetraisopropoxide in a suspension containing phosphide. The P-doped TiO2 nanoparticles exhibited a pale yellow color. The UV-vis diffuse reflection spectra of P-doped TiO2, which was calcined at 450-600 degrees C, showed a continuous and tailing absorption in the visible region. XRD patterns of P-doped TiO2 showed the presence of anatase phase up to a temperature of 500 degrees C and the appearance of rutile phase from a temperature over 550 degrees C. The red shift of the absorption edge was not associated with the phase transformation from anatase to rutile. The XPS P2p spectra of P-doped TiO2 indicated the decrease of P5+ and the increase of P3- during sputtering. The results suggested the presence of phosphate on the surface and the presence of P3- on the inner side of P-TiO2. The action spectra of photocatalytic reaction for acetaldehyde decomposition revealed visible light activity of P-doped TiO2. P-doped TiO2 calcined at 475 degrees C was the most active in degradation of phenol under visible light. The P-content was found to play a key role in determining the spectral response in visible area and the photocatalytic activity under visible light irradiation. (c) 2012 Elsevier B.V. All rights reserved.