<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "Investigation of dye-functionalized\r\nTiO2 nanoparticles using vibrational\r\nsum-frequency-generation\r\nspectroscopy"^^ . "The steadily increasing demand for energy worldwide has resulted in the depletion of the existing\r\nfossil energy resources and the pollution of the atmosphere by greenhouse gases such as\r\nCO2, which are responsible for global warming. To curb these problems, research activities aiming\r\nat CO2 conversion into value-added products, e.g. fuels like methanol, using sunlight have\r\nintensified over the last few years. In this work, TiO2 nanoparticles functionalized with perylene-based\r\ndyes containing either a carboxylic acid or anhydride group as molecular anchor to the\r\nTiO2 surface were studied as potential photocatalyst for solar light-driven CO2 reduction. The\r\ndye binding geometry is of particular importance since it influences the electron transfer from the\r\ndye to TiO2 and hence the photocurrent output of any given dye/TiO2 system. Two dyes, ID1157\r\nand ID1152, structurally identical apart from their anchor group, were selected to allow direct\r\ncomparison. In addition, a simple model substance bearing an anhydride group was investigated\r\nto facilitate the interpretation of the lesser known anhydride binding mode. Surprisingly, despite\r\ntheir structural similarity, the observed photocurrent amplitude of the ID1157/TiO2 system\r\ncontaining a carboxylic acid anchor was much higher than for the ID1152/TiO2 system containing\r\nan anhydride anchor. With the help of ultraviolet/visible (UV/Vis) absorption, infrared (IR),\r\nRaman and vibrational sum-frequency generation (VSFG) spectroscopy it was sought to determine\r\nwhether the photocurrent signals were correlated to the dissimilar anchor groups and their\r\nbinding modes. From the UV/Vis spectra it was found that the anhydride group opened upon\r\nbinding. As for the IR and Raman studies it could be concluded that the carboxylic acid anchor\r\nof ID1157 and both carboxylate groups of the opened anhydride of ID1152 bound via a bidentate\r\nbridging pattern. Furthermore, it was shown from the background-suppressed VSFG spectra of\r\nthe bound dyes in air and water that these adsorbed in an orderly fashion, ID1157 more so than\r\nID1152, but with both only slightly disturbed in the presence of water. In addition, it was found\r\nthat all molecules in the ID1157 dye layer were adsorbed on the TiO2 surface via chemisorption.\r\nBy contrast, the ID1152 dye layer was composed of chemisorbed as well as physisorbed dyes, the\r\nlatter being coordinated via a closed anhydride group. Also, ID1157 displayed a higher surface\r\ndensity of adsorbed molecules compared to ID1152. From a preliminary polarization analysis, it\r\nwas suggested that the dyes with carboxylic acid anchor adopted a tilted binding geometry. In\r\nview of the results obtained on the binding geometry of the dyes ID1157 and ID1152 it was possible\r\nto identify some criteria important for the generation of a high photocurrent: 1) binding of\r\nthe dye via chemisorption with 2) a high surface density and possibly through 3) a tilted geometry.\r\nThese findings have important implications for the understanding of the mechanism of dye\r\nfunctionalization. Finally, methanol and CO2 adsorption on TiO2 films was investigated by VSFG\r\nspectroscopy. Only molecularly adsorbed methanol was observed which was easily displaced\r\nby water or methanol/water mixtures. However, CO2 adsorption could not be detected in the\r\nspectral range which was investigated."^^ . "2012-11-16" . . . . . . . "Anna"^^ . "Keese"^^ . "Anna Keese"^^ . . . . . . "Investigation of dye-functionalized\r\nTiO2 nanoparticles using vibrational\r\nsum-frequency-generation\r\nspectroscopy (PDF)"^^ . . . "AKeesePhDthesis(2012)-final.pdf"^^ . . . "Investigation of dye-functionalized\r\nTiO2 nanoparticles using vibrational\r\nsum-frequency-generation\r\nspectroscopy (Other)"^^ . . . . . . "indexcodes.txt"^^ . . . "Investigation of dye-functionalized\r\nTiO2 nanoparticles using vibrational\r\nsum-frequency-generation\r\nspectroscopy (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "Investigation of dye-functionalized\r\nTiO2 nanoparticles using vibrational\r\nsum-frequency-generation\r\nspectroscopy (Other)"^^ . . . . . . "preview.jpg"^^ . . . "Investigation of dye-functionalized\r\nTiO2 nanoparticles using vibrational\r\nsum-frequency-generation\r\nspectroscopy (Other)"^^ . . . . . . "medium.jpg"^^ . . . "Investigation of dye-functionalized\r\nTiO2 nanoparticles using vibrational\r\nsum-frequency-generation\r\nspectroscopy (Other)"^^ . . . . . . "small.jpg"^^ . . "HTML Summary of #14023 \n\nInvestigation of dye-functionalized \nTiO2 nanoparticles using vibrational \nsum-frequency-generation \nspectroscopy\n\n" . "text/html" . . . "500 Naturwissenschaften und Mathematik"@de . "500 Natural sciences and mathematics"@en . . . "540 Chemie"@de . "540 Chemistry and allied sciences"@en . .