| Abstract [eng] |
Titanium dioxide (TiO2) has been studied for many years in a vast range of applications. TiO2 is white solid inorganic substance with unique dielectric and optical properties and is considered as not hazardous material and could be modified depending on requirements for specific applications. Nevertheless, TiO2 manufacturing is cheaper than materials with similar properties. TiO2 has great potential in energy and environmental researches, such as lithium ion batteries, self-cleaning coatings, water purification or as a photocatalyst. TiO2 shows tremendous exciton producing under visible and UV radiation. TiO2 bandgap is ~3,2 eV, its conduction band minimum (CBM) is almost as same as hydrogen potential, while valence band maximum (VBM) is slightly lower ~ 1,6 eV than oxygen potential. Seeing that VBM is low, light absorbance of TiO2 is restricted to 5% of all visible light radiation. That means that only UV radiation can cause the photocatalysis process effectively. This could be modified with other conductive materials such as metals or polymers. The main thing in photocatalysis process is conductivity of material and low recombination of excitons is the main parameter for material. TiO2 shows relatively fast recombination of excitons and low light absorbance but this could be controlled with other materials. Metal ions or polymers plays the second role in photocatalysis as generators of excitons or as photosensitizers, raising light absorbance under visible light. The aim of this research is finding optimal concentration of Cu-, Ni-, Mg- in TiO2 thin films using physical vapor deposition for separation of oxalic acid molecules under UV light. Magnetron sputtering is one of the most acceptable method for TiO2 thin films deposition, but the method is quite complicated to make m-doped TiO2 thin films. The DC, pulsed DC and RF magnetron sputtering technology, XRD, TOC and SEM analysis methods were used to analyze and calibrate photocatalysis efficiency. The results of photocatalysis shows optimal concentration of dopants apparent rate constant for different samples. Higher or lower concentration of dopants reduce photocatalytic efficiency. XRD, SEM and EDS analysis shows that reducing concentration of dopant in TiO2 reduces the stability of system, but raises the activity of surface area. |
