Biomimetic TiO{sub 2} photocatalysis: A model system for pyotosynthesis

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Illumination of semiconductor colloids with light having energy greater than the band gap leads to the formation of electron/hold pairs. Similar to the natural photosynthetic systems, rapid recombination of photogenerated carriers is prevented by removal of one or both carriers from the semiconductor particle. Since the lifetime of charged pairs is very short, only very fast reactions with adsorbed species lead to efficient charge separation. Concurrently, surface adsorption also results in the blocking of the surface states that thermalize photogenerated charges and convert useful energy into heat. Thus, if the surface of the colloid is properly engineered the kinetics of ... continued below

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4 p.

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Thurnauer, M.C.; Rajh, T. & Tiede, D.M. March 1, 1996.

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Illumination of semiconductor colloids with light having energy greater than the band gap leads to the formation of electron/hold pairs. Similar to the natural photosynthetic systems, rapid recombination of photogenerated carriers is prevented by removal of one or both carriers from the semiconductor particle. Since the lifetime of charged pairs is very short, only very fast reactions with adsorbed species lead to efficient charge separation. Concurrently, surface adsorption also results in the blocking of the surface states that thermalize photogenerated charges and convert useful energy into heat. Thus, if the surface of the colloid is properly engineered the kinetics of the photochemical reactions and the redox properties of photogenerated charges in the modified colloids may be enhanced for stabilized charge separation, such as in natural photosynthesis. We have shown that adsorption of {alpha}-substituted mercapto-carboxylic acids on small particle TiO{sub 2} colloids results in the bidentate coordination of surface Ti atoms with carboxyl and mercapto groups. This complex is stabilized by the formation of a five membered ring which is the optimal configuration for octahedral coordination of Ti atoms. This surface modification of TiO{sub 2} results in the formation of a charge transfer complex that shifts the optical absorption threshold to the visible region of the spectrum (520 nm). These complexes provide more favorable absorbance properties for solar energy conversion. In this work we are applying electron paramagnetic resonance (EPR) to study the transient species formed by the reactions initiated by charge transfer or colloid photoabsorption.

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4 p.

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OSTI as DE96006694

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  • 3. biennial Trombay symposium on radiation and photochemistry, Bombay (India), 8-12 Jan 1996

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  • Other: DE96006694
  • Report No.: ANL/CHM/CP--87993
  • Report No.: CONF-960169--1
  • Grant Number: W-31109-ENG-38
  • Office of Scientific & Technical Information Report Number: 206429
  • Archival Resource Key: ark:/67531/metadc669663

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  • March 1, 1996

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  • June 29, 2015, 9:42 p.m.

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  • Dec. 14, 2015, 5:18 p.m.

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Thurnauer, M.C.; Rajh, T. & Tiede, D.M. Biomimetic TiO{sub 2} photocatalysis: A model system for pyotosynthesis, article, March 1, 1996; Illinois. (digital.library.unt.edu/ark:/67531/metadc669663/: accessed May 25, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.