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Highly Efficient Formation of TiO2-XNX–Based Photocatalysts - Potential Applications For Active Sites in Microreactors, Sensors, and Photovoltaics
Published online by Cambridge University Press: 01 February 2011
Abstract
We have produced nitrogen doped, stable, and environmentally benign TiO2-xNx photocatalysts whose optical response can be tuned across the entire visible region using a nanoscale exclusive synthesis route, performed in seconds at room temperature. This synthesis, which can be simultaneously accompanied by metal atom seeding, that can be accomplished through the direct nitration of anatase TiO2 nanostructures with alkyl ammonium salts. Tunability throughout the visible spectrum depends on the degree of TiO2 nano- particle agglomeration and the influence of metal seeding. The introduction of a small quantity of palladium, in the form of the chloride or nitrate, promotes further nitrogen uptake, appears to lead to a partial phase transformation, displays a counter ion effect with the acetate, and produces a material absorbing well into the near infrared. The nitridation process also induces the formation of oxygen hole centers. Silver introduced as the nitrate into a TiO2 or TiO2-xNx nanostructure framework, forms seeded AgxO - TiO2 or TiO2-xNx nanostructure mixtures which can be induced to self-assemble and to agglomerate into nano-needle and planar arrays using select metal probes. Surprisingly, no organics are incorporated into the final TiO2-xNx products. These visible light absorbing photocatalysts readily photodegrade methylene blue and when used to create photocatalytic sites on a surface based microreactor induce ethylene oxidation with visible light. They can be transformed from liquids to gels and placed on the surfaces of sensor and microreactor based configurations to 1) facilitate a photocatalytically induced solar pumped sensor response, and 2) provide a possible means for the catalytically induced disinfection of airborne pathogens. In contrast to a process which is facile at the nanoscale, we find little or no direct nitridation of micrometer sized anatase or rutile TiO2 powders at room temperature. Thus, we demonstrate an example of how a traversal to the nanoscale can vastly improve the efficiency for producing important submicron materials.
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- Research Article
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- Copyright © Materials Research Society 2004
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