Metallorganic chemical vapor deposition and characterization of TiO2 nanoparticles

TiO2 nanoparticles were synthesized using metallorganic chemical vapor deposition process. Particles with and without metal ion dopants were obtained. X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy measurements confirmed the stoichiometry of the TiO2 nanoparticles. X-ray diffraction patterns showed a polycrystalline anatase structure of TiO2. Transmission electron microscopy revealed that these particles are of nanoscale dimensions. Exact particle size and size distribution analyses were done by dynamic light scattering. The average particle size was determined to be 22 nm. The nanosize particles provide large surface area for photocatalysis and a large number of free surface charge carriers which are crucial for the enhancement of photocatalytic activity. In order to improve the photocatalytic activity, metal ions, including transition metal ions (Pd2+, Pt4+, Fe3+) and lanthanide ion (Nd3+) were added to pure TiO2 nanoparticles. The effects of dopants on photocatalytic kinetics were investigated by the degradation of 2-chlorophenol under an ultraviolet light source. The results showed that the TiO2 nanoparticles with the metal ion dopants have higher photocatalytic activity than undoped TiO2. Nd3+ showed the largest enhancement. The difference in the photocatalytic activity with different dopants is related to different ionic radii of the dopants. (C) 2002 Elsevier Science B.V. All rights reserved.