Vliv metody přípravy C3N4 a modifikování platinou na fotokatalytický rozklad oxidu dusného

Abstract

This bachelor thesis is focused on the photocatalytic decomposition of nitrous oxide in the presence of photocatalysts on the base of carbon nitride. The main goal of this work is to decompose one of the most important greenhouse gases, namely nitrous oxide, on to the natural components of the environment into oxygen and nitrogen by using prepared photocatalysts. The g-C3N4 a p-C3N4 photocatalysts were prepared in two different ways and the Pt/g-C3N4 and Pt/p-C3N4 nanocomposites were prepared by depositing platinum metal on to the surface of C3N4 by using in situ photo deposition method. Physico-chemical properties of photocatalysts were characterized by X-ray powder diffraction, infrared spectroscopy, UV Vis spectroscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, photoelectrochemical measurements, scanning and transmission electron microscopy. The photocatalytic decomposition of N2O in the presence of the prepared photocatalysts was carried out in stainless steel batch photoreactor and an 8 W Hg lamp with a wavelength of 254 nm was used as a radiation source, which was placed in a quartz tube in the middle of the photoreactor. The photocatalytic decomposition of N2O was studied over a time interval of 0-14 hours. The photolysis was also studied, when the decomposition of N2O took place only in the presence of UV radiation without the participation of a photocatalyst. From the evaluation of the experimental data of the photocatalytic decomposition of nitrous oxide, it was found that the highest conversion of N2O after 14 hours was achieved in the presence of the photocatalyst p-C3N4. The values of N2O conversion decreased after 14 hours of irradiation in the order of: p-C3N4 > g-C3N4 > 3%Pt/p-C3N4 > 3%Pt/g-C3N4 > photolysis. Increased photocatalytic activity of polymeric C3N4 was caused by the method of preparation, which made it possible to prepare a material with a higher specific surface area and a lower rate of recombination of the generated charges. The obtained results are in accordance with the photoelectrochemical measurement.