engleski

Modified TiO2 Based Nanostructures for Photocatalysis

Increasing awareness of harmful consequences of persistent organic pollutants in water makes development of cheap and stable photocatalysts for their degradation one of significant goals in environmental engineering. Materials based on nanostructured TiO2 are among the most prominent materials of the last 40 years that have been studied for the purpose of use in photocatalysis. One of the main limitations for the application of TiO2 in materials photocatalysis is a wide energy bandgap, Eg = 3.2 eV, so its application is limited to UV radiation. In order to increase the efficiency of the TiO2 nanostructure as a photocatalyst and expand the spectral range in which the photocatalyst is activated, different approaches to modifications of the synthesized nanoparticles of TiO2 were applied. In this study the photocatalytic degradation of water pollutant will be examined using different nanostructures of TiO2-based photocatalysts. The strategies used for the improvement of their photocatalytic activity in UV region as well as broadening of their activity in visible and near IR light, will be presented. The synthesis of TiO2 nanostructures (nanotubes- NT, and nanoparticles- NP) was obtained by electrochemical oxidation in organic electrolyte and hydrothermal syntheses for preparation of NT, or by pulsed laser ablation (PLA) for preparation of NP. Surface modification and decoration with silver nanoparticles was done by photo-reduction, while decoration with FeOOH/Fe2O3 was achieved by hydrothermal synthesis. The additional processing in reduction atmosphere was also occasionally applied. The structural properties of studied photocatalysts were investigated by X-ray powder diffraction (XRD), Raman spectroscopy, scanning and transmission electron microscopy (SEM and TEM), while the photocatalytic degradation was studied using different model pollutants from simple dyes as methylene blue, or caffeine to serious industrial and pharmaceutic pollutants as 2, 5-dihydroxybenzoic acid, or salicylic acid. It was shown that the photocatalytic activity of studied nanostructures was considerably increased by optimization of the TiO2-based materials bandgap to obtain absorption in the visible and near-IR regions of the solar irradiation by decoration with Ag or FeOOH/Fe2O3 nanoparticles, and/or by introducing defects in reduction atmosphere. The improvement of photocatalytic properties of TiO2 nanoparticles 9th International Advances in Applied Physics & Materials Science Congress & Exhibition Published: November, 2019 53 prepared by PLA were obtained by increase of the active surface by decreasing the size of TiO2 photocatalyst nanoparticles and by introducing some content of TiO2 of Magneli phases. The shift of the photocatalytic activity in the visible and near- IR regions of the spectrum would allow the work of photocatalytic reactors for purification of the water using only sun light without appliance of additional UV lamps. The photocatalytic properties of the synthesized photocatalysts will be discussed considering the morphology, crystal structure and the atomic percentage of the decoration.

TiO2 ; nanostructures ; structural characterization ; photocatalysis

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