Analýza vztahu mezi optickými/elektronovými/texturními/strukturními vlastnostmi dopovaných TiO2 nanomateriálů a jejich aktivitou ve fotokatalýze

Abstract

The thesis deals with relation between optical/ electronic/ textural and structural features of neodymium doped TiO2 nanomaterials and their photocatalytic activity during decomposition of methanol. The essential aim of photocatalytic methanol decomposition is production of hydrogen. Pure TiO2 and neodymium doped TiO2 photocatalyst (0,2; 0,5; 0,8; 1,0 a 1,5 hm % Nd) were concocted by using the sol-gel method. The resulting photocatalysts were concocted by X-ray fluorescence spectroscopy, X-ray diffraction, nitrogen physisorption, ultraviolet-visible spectrometry and photoelectrochemical measurements. Photocatalytic decomposition of methanol was performed in annular batch reactor with suspended photocatalysts. As a source of illumination 8 W Hg lamp (λ = 254 nm) was used, which was located in the center quartz glass of the reactor lid. Photolytic decomposition of methanol was performed without presence of a photocatalyst. The object of study the mentioned methanol decomposition was hydrogen. The effect of neodymium doping on photocatalytic decomposition was monitored in a time interval of 0-4 hours. The extract of hydrogen yielded by photocatalytic decomposition of methanol in presence with all prepared photocatalysts were higher than during the photolysis independently. Decrease of hydrogen extract was following: 0,2 hm. % Nd/TiO2 > TiO2 > 1 hm. % Nd/TiO2 > 0,8 hm. % Nd/TiO2 > 0,5 hm. % Nd/TiO2 > 1,5 hm. % Nd/TiO2. The most active photocatalyst was doped with 0,2 hm. % Nd. Defects in the grid were the major influencing parameter photocatalytic decomposition, which conducted like being held in electron traps. This effect increased lifetime of photogenerated electron-hole pairs, and thus enhancing the photocatalytic efficiency.