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Plasmon Sensitized TiO2 Nanoparticles as a Novel Photocatalyst for Solar ApplicationsEPA Grant Number: R829603
Title: Plasmon Sensitized TiO2 Nanoparticles as a Novel Photocatalyst for Solar Applications
Investigators: Chumanov, George
Institution: Clemson University
EPA Project Officer: Lasat, Mitch
Project Period: July 1, 2002 through June 30, 2005 (Extended to June 30, 2006)
Project Amount: $320,000
RFA: Exploratory Research: Nanotechnology (2001) RFA Text | Recipients Lists
Research Category: Safer Chemicals , Nanotechnology
Efficient conversion of sunlight into electrical and/or chemical energy is of great technological importance for modern society and future generations. One attractive possibility for utilization of solar energy is based on the ability of small semiconductor particles to function as photocatalysts promoting various oxidation and reduction reactions under sunlight. Titanium dioxide (TiO2) is the most promising material for such applications because it is an efficient, environmentally friendly, and relatively inexpensive photocatalyst. However, wide technological usage of this photocatalyst is largely hindered by the fact that ultraviolet light that does not constitute a significant fraction of the solar spectrum that is required for its activation. Any improvement of photocatalytic efficiency of TiO2 by shifting its optical response from UV to the visible spectral range will have a profoundly positive effect. The main objective of the proposed research is to synthesize and test a novel photocatalyst that consists of small silver or gold nanoparticles covered with a thin TiO2 shell. Silver and gold nanoparticles are very efficient systems for the interaction with visible light due to the excitation of plasmon resonances. It is expected that, due to the coupling of plasmon resonances in the core with the electron-hole pair generation in the shell, these hybrid Ag/Au TiO2 nanoparticles will exhibit photocatalytic activity in the visible spectral range thereby more efficiently utilizing solar energy.
Coating of silver and gold nanoparticles of different sizes with TiO2 layers of various thickness will be accomplished by sol-gel chemical reactions. High temperature calcination and hydrothermal treatment will be used to convert amorphous TiO2 layers into the anatase form. Other hybrid nanoparticles include open TiO2 shell around metal cores, hollow TiO2 nanoparticles, and Ag/Au@TiO2 particles with small RuO2 and Pt clusters attached to their surface. All particles will be characterized by UV-Vis absorption, luminescence and Raman scattering spectroscopy, electron and scanning tunneling microscopy, and x-ray diffraction. The photocatalytic activity of hybrid nanoparticles will be assessed in model experiments using photoreduction of methylviologen and photocatalytic degradation of 4-chlorophenol.
Ag/Au@TiO2 particles represent a new system with unknown chemical and physical properties. These nanoparticles will exhibit enhanced photocatalytic activity as compared to TiO2 conventional catalyst. This new material will have positive impact on the development of new solar based technologies including (photo)remediation of environmental pollutants, photovoltaic cells, photochemical splitting of water, and artificial photosynthesis. The synthetic approaches developed for the preparation of Ag/Au@TiO2 hybrid nanoparticles particles can be extended to include other metals and semiconductors. The proposed research will answer the fundamental question about the possibility of utilization of energy stored in the form of plasmon resonances in metal nanoparticles to carry different chemical reactions.