Study of Nd3+, Pd2+, Pt4+, and Fe3+ dopant effect on photoreactivity of TiO2 nanoparticles

The metallorganic chemical vapor deposition method was successfully used to synthesize pure TiO2 and Nd3+-, Pd2+-, Pt4+-, and Fe3+-doped TiO2 nanoparticles. Polycrystalline TiO2 structure was verified with x-ray diffraction, which showed typical characteristic anatase reflections without any separate dopant-related peaks. Transmission electron microscopy observations confirmed the existence of homogeneously distributed 22 +/- 3 nm TiO2 nanoparticles. The particle size remained the same for the doped samples. The doping level of transition metals was kept at approximate to1 atomic percent, which was determined by x-ray photoelectron spectra and energy dispersive x-ray spectroscopy. The effects of different types of dopants on the photocatalytic activity were revealed by the degradation of 2-chlorophenols with an UV light source. The photocatalytic efficiency was remarkably enhanced by the introduction of Pd2+ and Nd3+. Nd3+-doped TiO2 showed the largest enhancement. However, Pt4+ changed the 2-chlorophenol degradation rate only slightly, and Fe3+ was detrimental to this process. These effects were related to the position of the dopants in the nanoparticles and the difference in their ionic radii with respect to that of Ti4+.