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New aerogels retain quantum dot properties With their highly porous structure, vast surface area, and low density, aerogels have potential applications in catalysis, filtration, and insulation. However, until now most of these inorganic polymers have been made out of metal oxides, limiting the kinds of chemistry the materials can do. Scientists at Detroit's Wayne State University have, for the first time, prepared mesoporous semiconducting aerogels out of metal chalcogenides such as CdS, CdSe, ZnS, and PbS [Science, 307, 397 (2005)]. Stephanie L. Brock, Jaya L. Mohanan, and Indika U. Arachchige make the materials by oxidatively removing surface groups from chalcogenide quantum dots. These nanoparticles assemble into a loosely joined network that the group then dries using supercritical CO2 to form the aerogel. Remarkably, this macroscopic structure retains the optical properties of its quantum dot building blocks. Brock reckons the material would be ideal for photocatalysis or for making highly porous semiconductor sensors. She also notes that the strategy for making aerogels is quite general and could be used with other types of nonoxide compounds |
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