AVS 54th International Symposium
    Renewable Energy Science & Technology Topical Conference Thursday Sessions
       Session EN+SS+TF-ThM

Paper EN+SS+TF-ThM1
Thermal and Photoreactions of Catechol on TiO2

Thursday, October 18, 2007, 8:00 am, Room 602/603

Session: Surface Science Challenges for Solar Energy Conversion
Presenter: P. Jacobson, Tulane University
Authors: P. Jacobson, Tulane University
X.-Q. Gong, Princeton University
M. Connors, Princeton University
A. Selloni, Princeton University
U. Diebold, Tulane University
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The wide band gap of titanium dioxide limits its use as a photocatalytic and photovoltaic material with solar radiation as its source. One method to increase the absorption of light at visible wavelengths is by attaching metallo-organic dye complexes. These dyes frequently use catechol and phosphonic or carboxylic acids to link the dye to the titanium dioxide surface. In an attempt to better understand the adsorption of these complex dyes, we have studied the adsorption of catechol (1,2-benzenediol) on the (110) and (011) faces of rutile titanium dioxide. Catechol was preferred over ‘real’ dye complexes for its ease of deposition under high vacuum conditions and simple chemical makeup. Ultraviolet photoemission spectroscopy shows a gap state introduced to the TiO2 upon catechol adsorption. Increases in the Oxygen 1s shoulder in XPS indicate dissociative adsorption of catechol and formation of surface hydroxyls. For catechol adsorption on the rutile (110) surface a 3x1 overlayer results. Similarly, adsorption on the (011) surface forms a 2x1 overlayer. Formation of surface hydroxyls upon adsorption is believed to play a role in the formation of these ordered structures. To further study the catechol - titanium dioxide complex, temperature dependent measurements using STM, XPS, and UPS were made in the presence and absence of molecular oxygen. The difference in decomposition and intermediates formed will be discussed. These techniques were also used to study UV induced photoreactions of catechol on TiO2.