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Proceedings Paper

Nanostructures and porous silicon: activity and phase transformation in sensors and photocatalytic reactors
Author(s): James L. Gole; Stephen E. Lewis; Andrei Fedorov; Sharka Prokes
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Paper Abstract

Porous interfaces are being transformed within the framework of nanotechnology to develop highly efficient sensors, nanostructure modified microreactors, and active battery electrodes. We demonstrate the rapid and reversible sensing of HCl, NH3, CO, SO2, H2S, and NOx at or below the ppm level. Gold and tin-based nanostructured coatings are introduced to improve the detection of NH3, CO, and NOx as these coatings form the initial basis for introducing significant selectivity. These sensor suites are being extended to develop microreactors, with a goal to introduce quantum dot (QD) based photocatalysts within the porous interface structure. Highly efficient, visible light absorbing, anatase TiO2-xNx nanophotocatalysts have been formed in seconds at room temperature via the direct nitridation of anatase TiO2 nanocolloids. A tunability throughout the visible is found to depend upon the degree of nanoparticle agglomeration and upon the ready ability to seed these nanoparticles with metal (metal ions) including Pt, Co, and Ni. This metal ion seeding also leads to unique efficient phase transformations, including that of anatase to rutile TiO2, at room temperature. The visible light absorbing photocatalysts readily photodegrade methylene blue and gaseous ethylene. They can be transformed from liquids to gels and, in addition, can be placed on the surfaces of sensor and microreactor based configurations 1) to produce an improved photocatalytically induced solar based sensor response, and 2) with a goal to facilitate catalytically induced disinfection of airborne pathogens. In contrast to the nitridation 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 illustrate an example of how a traversal to the nanoscale can vastly improve the efficiency for producing important submicron particles.

Paper Details

Date Published: 18 August 2005
PDF: 12 pages
Proc. SPIE 5929, Physical Chemistry of Interfaces and Nanomaterials IV, 592908 (18 August 2005); doi: 10.1117/12.616892
Show Author Affiliations
James L. Gole, Georgia Institute of Technology (United States)
Stephen E. Lewis, Georgia Institute of Technology (United States)
Andrei Fedorov, Georgia Institute of Technology (United States)
Sharka Prokes, Naval Research Lab. (United States)


Published in SPIE Proceedings Vol. 5929:
Physical Chemistry of Interfaces and Nanomaterials IV
Clemens Burda; Randy J. Ellingson, Editor(s)

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