| Abstract
| - Porous polymeric beads have been used as templates for the fabrication of porous metaloxide spheres. The beads were soaked in sols of titanium dioxide, zirconium dioxide, ironoxide, aluminum oxide, indium oxide, tin oxide, and cerium oxide. Successful infiltrationand templating was obtained for titania, zirconia, tin oxide, and ceria giving monodisperse,nonaggregated spheres with a porous surface and inner structure. The use of iron andaluminum oxide sols resulted in cracked spheres with excess oxide material on the spheresurfaces, and in the case of indium oxide, broken, hollow, shell-like structures were produced.Combining the iron, aluminum, or indium oxide sols with the titania sol, at a 1:1 weightratio, and impregnating the template produced inorganic spheres containing the two metaloxides. The photocatalytic properties of the titania and mixed titania/indium oxide sphereswere studied by monitoring the decomposition of 2-chlorophenol as a function of time andsolution pH. Both the porous titania and mixed titania/indium oxide spheres were moreefficient photocatalysts than Degussa P25 titania, a commercial standard. Optimum solutionpH for the photocatalytic reaction was determined to be pH 6 for the titania spheres andpH 4 for the titania/indium oxide sample. Pyridine adsorption on the mixed titanium/indiumoxide spheres showed FTIR peak shifts similar to those of the indium oxide spheres, whichindicated the presence of stronger Lewis acid sites compared with the titania spheres.
- Porous metal oxide spheres have been fabricated by using polymer bead templates and the infiltration of preformed metal oxide nanoparticles. The spheres have a diameter of 5−6 μm. The titanium dioxide and TiO2/In2O3 spheres were photocatalytically more active than Degussa P25 titania for the decomposition of 2-chlorophenol.
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