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1 Schools of Physics and Mechanical and Chemical Engineering,
Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA
2 Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106, USA
| Enhanced reactivity and phase transformation is characterized at the nanoscale. Silica/silicon (SiOx) nanospheres of diameter ≥ 30 nm generated from equimolar Si/SiO2 mixtures are found to display enhanced catalytic and reactive properties relative to commonly employed silica support surfaces including fumed silica. This behavior has suggested the possibility of extremely efficient doping and metal seeding involving TiO2 nanocolloids. The unique reactivity and ready transformation which is found to accompany the facile (seconds) room temperature nitration of TiO2 nanocolloids, efficiently produces photocatalytically active TiO2-xNx nanoparticles absorbing light well into the visible region. The introduction of a small quantity of palladium in the form of the chloride or nitrate promotes increased nitrogen uptake, appears to lead to a partial phase transformation, displays a counterion effect (including the acetate), and produces photocatalytic materials absorbing well into the infrared. Additional metal oxides and metals can be used to create doped and seeded materials which can be transformed from liquids to gels facilitating their deposition on surfaces and into porous media. In distinct contrast, attempts to nitride micron-sized TiO2 particles do not result in the conversion to the oxynitride at room temperature. |
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