Origin of the face dependent
photocatalytic activity of TiO2:
probing surface chemistry with molecular adsorption
EMSL Project ID
9092
Abstract
Its wellknownproperties make titanium oxide (TiO2) an excellent model system for
studying photocatalysis. The (011) surface of TiO2 is the most reactive TiO2 surface for
certain reactions. Until very recently, however, the atomic structure of the TiO2(011)
surface was unknown. Using scanning tunneling microscopy (STM) combined with
theoretical calculations of our collaborator Prof. Annabella Selloni at Princeton
University we were able to determine the structure of the TiO2(011) surface. This surface
forms a stable (2x1) reconstruction and is terminated by onefold
coordinated oxygen
atoms, a feature that distinguishes it from all other known TiO2 surfaces. We believe that
the unique structure of the TiO2(011)(
2x1) surface is the origin of its high photocatalytic
activity.
Only combined investigations of atomicscale
structures such as molecular adsorption
geometries, electronic properties, and chemical reactions can give a complete picture of
the fundamental processes during photocatalysis. Therefore, we propose to use thermal
desorption spectroscopy (TPD) for monitoring reaction dynamics and highresolution
electron energy loss spectroscopy (HREELS) for studying the electronic structure of
molecular adsorbates such as water and small organic molecules on TiO2(011). We will
use use ultraviolet light exposure to investigate photocatalysis on TiO2(011).
These experiments will be done at the Environmental Molecular Sciences Laboratory
(EMSL) of the Pacific Northwest National Laboratories (PNNL) in collaboration with Dr.
Michael A. Henderson. Here, we apply for funding supporting one graduate student and
one postdoctoral
fellow to travel to EMSL and to perform TPD and HREELS
measurements at EMSL. These experiments will complement the STM investigations on
water adsorption we are currently doing in our lab at Tulane University as well as our
ultraviolet
photoemission spectroscopy (UPS) studies at the Center for Advanced
Microstructures and Devices (CAMD).
The results of the proposed collaboration with EMSL will promote the fundamental
knowledge of photocatalysis. Photocatalytic processes on metal oxide surfaces have a
wide range of potential applications in areas such as waste water treatment, disinfection
of medical facilities, and solar energy conversion. A deeper knowledge of the origin of
the photocatalytic activity of TiO2 may result in the development of new or improved
applications. Conducting experiments in the interdisciplinary research environment at
EMSL will also be an invaluable educational experience for the graduate student and
provide professional insights for the postdoctoral
fellow. They will benefit from
working with EMSL's stateoftheart
equipment and the contact with EMSL's diverse scientists in the area of environmental sciences.
Project Details
Project type
Exploratory Research
Start Date
2004-09-13
End Date
2005-10-03
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
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