Titanium oxide aerogels prepared from titanium metal and hydrogen peroxide

The reaction of hydrogen peroxide with excess titanium metal produces rigid titanium oxide aquagels. Subsequent solvent exchanges with ethanol and carbon dioxide, and supercritical drying produces the corresponding aerogels. The aerogels are translucent yellow in appearance, are amorphous to X-rays, and have a BET surface area of 350 m(2)/g. The empirical formula of the material, as prepared, is TiO3H2.7C0.35. Infrared spectroscopy indicates the presence of peroxide and carbonate groups. The microstructure of the aerogel consists of a network of elongated particles 2-5 nm in diameter and tens of nm in length. Thermal treatment under argon at 473 K causes rapid decomposition of the aerogel, forming a blue-gray powder consisting of a mixture of rutile and anatase with a surface area of 80 m(2)/g. Additional thermal treatment at 973 K under air forms predominantly rutile, with a surface area of 20 m(2)/g. (C) 1998 Elsevier Science B.V.