title: Spectroscopic characterization of dye sensitized TiO₂ with CO₂ co-adsorption and visible light excitation
creator: Pöttinger, Leo
subject: ddc-530
subject: 530 Physics
description: The carbon dioxide (CO₂) reduction to hydrocarbons is a promising route to renewable fuels. Mechanistic studies on a new catalyst for visible light absorption and CO₂  conversion reveal the structural and chemical challenges of the CO₂ reduction. Organic dyes are bound to Titania (TiO₂) nanoparticles for visible light absorption.  The excited electrons are transferred to the catalyst where they provide energy for the catalytic process. The coordination and coverage of three selected anchoring  groups reveals the efficiency of electron injection into the TiO2 and their stability on the catalyst. Dyes with carboxylic acid and hydroxamic acid anchors bind via  a bidentate chelating coordination, whereas dyes with an anhydride group mostly bind in a two bidentate bridging coordinated pattern. This leads to an average  surface occupancy of 3.8·10−18 m^2 per anhydride dye molecule and 1.9·10−18 m^2 per carboxylic or hydroxamic acid dye molecules. The anhydride anchor shows the biggest structural change which leads to the highest observed hypsochromic shift upon adsorption of Delta Lambda anhydride = −80nm and is most stable when adsorbed. The highest electron injection efficiency is observed for the dye with a hydroxamic acid anchoring group.  The in-situ ATR IR spectroscopy of CO₂ saturated water adsorbed on dye sensitized TiO₂ shows a reduced carbonate formation with different adsorption coordination  compared to pure TiO₂, but no displacement of preadsorbed dyes. The addition of metal co-catalysts on TiO₂ does not influence the carbonate coordination. The photon  absorption and electron injection show promising results, whereas the carbonates are still chemically stable.
date: 2014
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/16122/1/DissertationLeoPoettinger.pdf
identifier: DOI:10.11588/heidok.00016122
identifier: urn:nbn:de:bsz:16-heidok-161227
identifier:   Pöttinger, Leo  (2014) Spectroscopic characterization of dye sensitized TiO₂ with CO₂ co-adsorption and visible light excitation.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/16122/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng