Fotokatalytická degradace oxidu dusnatého na tenkých filmech různým obsahem ceru dopovaného TiO2

Abstract

This Diploma thesis deals with an influence of modifying thin films of titanium dioxide by cerium for the photocatalytic degradation of nitric oxide. Photocatalysts TiO2 with cerium content of 0.7; 1.4 and 6.3 wt. % were prepared by the sol-gel method followed by calcination. Prepared photocatalysts were applied on concrete blocks and a glass plate. Prepared photocatalysts were characterized by X-ray diffraction analysis, X-ray fluorescence analysis, UV-Vis spectrometry and nitrogen physisorption. Photocatalytic activity of prepared photocatalysts was tested on decomposition of NO in a flow reactor constructed according an ISO 22197-1-2007 norm. A sample of photocatalysts, which was applied in a thin layer on concrete block or glass plate, was irradiated by a UV lamp through a glass visor with radiation of wavelength 365 nm. The optimal content of cerium on a thin layer of TiO2 was determined experimentally based on maximum conversion of NO. The conversion of nitric oxide during the photocatalytic degradation of NO decreased with increasing cerium content. The photocatalytic activity of prepared TiO2 thin layers decreased in this order: 0.7 wt. % Ce < 1.4 wt. % Ce < 6.3 wt. % Ce. The conversion of 30 % after stabilization was achieved in the presence of TiO2 thin film with 0.7 wt.% of cerium. The conversion of NO in the presence of TiO2 thin layers with higher content of cerium (1.4 and 6.3 wt. %) was significantly lower, 15 % and 5 %, respectively. The most active photocatalyst was also applied in a thin layer on a glass plate, whereas the measurement confirmed the assumption of low, basically zero, photocatalytic activity. This was probably caused by applying of a lower amount of photocatalyst and a lower adsorption of nitric oxide on smooth glass surface. The photocatalytic degradation of nitric oxide is a promising method of the future, especially after finding the optimal photocatalyst, which will increase the efficiency of the method and allow the photocatalytic degradation of nitric oxide in the range of visible light.