Grossmann, Henrike K.
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Item type:Publication, Structural and spectroscopic comparison between polycrystalline, nanocrystalline and quantum dot visible light photo-catalyst Bi 2 WO 6The structural and spectroscopic features of the visible light photocatalyst Bi2WO6 have been studied. Polycrystalline (PC), nanocrystalline (NC) and quantum dot (QD) sized samples were produced using solid state reaction, hydrothermal and flame spray pyrolysis methods, respectively. While the crystal structures of PC and NC Bi2WO6 are well characterized using X-ray powder diffraction data Rietveld refinements, the structural information of the QD are obtained from the complementary pair distribution function analysis and high-resolution transmission electron microscopy. The Raman spectra of the samples are compared with the phonon density of states calculated by DFT. A continuous phenomenological model describes selective optical phonon confinement into the QDs. The type of the electronic bandgaps obtained from the UV-VIS absorbance-spectra have been analyzed using two different methods, and compared with those calculated from the electronic band structures.journal article520 454 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Tailored aerosol synthesis of nanosized multicomponent catalysts(2018-01-29); ; ; Nanoparticles consisting of multiple components play a key role in the development of new materials and heterogeneous catalysts for novel types of energy conversion processes. This thesis demonstrates the flexibility of the Double Flame Spray Pyrolysis for the production of tailored multicomponent catalysts from almost all metals and transition metals by gas-to-particle conversion. Two experimental studies determine the optimal geometric process parameters of the two flames for the synthesis of highly active binary Fischer-Tropsch (FT) catalysts and ternary catalysts for the preferential oxidation of CO (CO-PrOx). Further investigates the thesis for the first time the main underlying process conditions during the double flame synthesis process e.g. the temperature profile of the intersecting flames and the mixing characteristic of the two components in the reaction zone. For the last one, two novel image based methods for the determination of the degree of mixing in deposited systems (active component on support: platinum (Pt) on titania (TiO2)) and in aggregated systems (two types of support: tungsten-oxide (WO3) and titania (TiO2)) are developed.doctoral thesis506 158