Synthesis and structural features of mesoporous NiO/TiO 2 nanocomposites prepared by sol-gel method for photodegradation of methylene blue dye

A novel series of mesoporous NiO/TiO 2 nanoparticles was successfully synthesized by sol-gel method using cetyltrimethylammonium bromide as controlling template in attempts to study the photodegradation of methylene blue dye. Structural and textural features of the composite samples were investigated by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherm, Fourier transformer infra-red (FTIR) and transmission electron microscope (TEM). The band energy gap of the samples was estimated using UV-vis spectrometer. A remarkable reduction in particle size to 4 nm and increasing the surface area up to 220 m 2/g is detected upon increasing nickel oxide contents revealing the successful role of dopants in controlling the crystal growth and pore structure of the catalyst. Nearly complete mineralization of methylene blue dye occur significantly at higher rate over doped samples compared with pure titanium oxide. The degradation of the dye follows a pseudo first-order kinetics and the apparent rate constant increases with increasing the nickel oxide content up to 5 mol%. The exceptional photocatalytic activity of the samples was attributed to reduction in particle size, increasing in surface area, photoelectron/hole separation efficiency and the extension of the wavelength range of photoexcitation. © 2012 Elsevier B.V.