Effect of metal-doping of TiO2 nanoparticles on their photocatalytic activities toward removal of organic dyes

Abstract

M-doped TiO 2 nanoparticles (M = Cu, Zn) were prepared by the sol–gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR and UV–vis spectroscopy techniques were used to characterize the samples. Photocatalytic activities of samples for methyl orange (MO) degradation and the chemical oxygen demand (COD) were investigated. XRD results confirmed the formation of the anatase phase for the TiO 2 nanoparticles, with crystallite sizes in the range of 9–21 nm. The small crystallite size and doping ions (Cu and Zn) inhibited any phase transformation and promoted the growth of the TiO 2 anatase phase. The optical study showed that doping ions lead to an increase in the absorption edge wavelength, and a decrease in the band gap energy of TiO 2 nanoparticles. The doped TiO 2 nanoparticles in general showed higher photocatalytic activities than the pure ones. The Cu doped TiO 2 nanoparticles showed the best photocatalytic activity based on the measured COD values.