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 ethan ol and carbon dioxide, and supercritical drying produces the correspon ding 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 em pirical formula of the material, as prepared, is TiO3H2.7C0.35. Infrar ed spectroscopy indicates the presence of peroxide and carbonate group s. The microstructure of the aerogel consists of a network of elongate d particles 2-5 nm in diameter and tens of nm in length. Thermal treat ment under argon at 473 K causes rapid decomposition of the aerogel, f orming a blue-gray powder consisting of a mixture of rutile and anatas e with a surface area of 80 m(2)/g. Additional thermal treatment at 97 3 K under air forms predominantly rutile, with a surface area of 20 m( 2)/g. (C) 1998 Elsevier Science B.V.