Příprava a charakterizace nanostruktur grafitizovaného C3N4 a TiO2 pro rozklad oxidu dusného

Abstract

This bachelor thesis deals with the preparation and characterization of g-C3N4 and TiO2 nanostructures for the decomposition of nitrous oxide, which were prepared and subsequently subjected to characterization using these available methods: transmission electron microscopy, physisorption, X-ray diffraction, infrared spectroscopy, UV-Vis spectroscopy, luminescence spectroscopy, Raman spectroscopy and photocatalytic decomposition of N2O. Bachelor thesis consists of theoretical and experimental part. In the theoretical part are pointed out the significance of the ozone layer and the importance of its protection. There is also included basic principle of photocatalysis, functioning of nanotechnologies and basic characteristics of graphitized C3N4 and TiO2. Used chemicals and instruments for characterization along with the parameters of these instruments are part of the experimental part. In addition, the preparation of the individual nanostructures of graphitized C3N4 and TiO2 and their mixtures in the weight ratio of 1:2, 1:4 and 1:6 is described in detail. The main part of the experimental part of the bachelor thesis is individual characterization, where each of them is presented along with partial results. The particle sizes of the pure TiO2 sample and the TiO2/C3N4 heterostructure (1:2) were evaluated by TEM. The highest frequency of pure TiO2 had nanoparticles measuring 10-11 nm and in the heterostructure the largest particle size measures 10-15 nm. Using the BET analysis, it was found that the highest specific surface area was pure TiO2 (59 m2/g) and the smallest specific surface area had g-C3N4 (27 m2/g). The XRD diffractogram, both infrared and Raman spectra, confirmed the presence of TiO2 in anatase phase and graphitized C3N4 in tri-s-triazine (XRD) and triazine structure (IR spectroscopy). TiO2 grains in the anatase phase and TiO2/g-C3N4 heterostructures (1:2) were counted as 11.9 nm and 13.1 nm. From DRS analysis, the energy values of the absorbent edges (band gaps) TiO2 and g-C3N4 were determined. Photoluminescent spectra at the end of the thesis confirm the formation of heterostructures between TiO2 and g-C3N4. The highest conversion of N2O was achieved in the presence of TiO2/C3N4 heterostructure (1:2), 68 % after 18 hours.