Effect of precursor structure on mixed-crystal phase titanium oxide synthesized by sol-gel reaction in supercritical carbon dioxide

Abstract

Effects of the precursor structure on crystallinity and morphology of titanium oxide from sol-gel reaction and drying in supercritical carbon dioxide was investigated. The titanium precursors examined in this work are: titanium isopropoxide (TIP), titanium tetrabutoxide (TBO), titanium ethylhexoxide (TEO) and titanium diisopropoxide bis(acetylacetonate) (TDB). A mixed-crystal phases with anatase and rutile phases were formed from the titanium oxide synthesized in supercritical carbon dioxide at the lower calcination temperatures. The formation of the rutile phase in the mixed-crystal titanium oxide was facilitated by using the TEO and TDB precursor with long alkyl chain and acetylacetonate group and the calcination in argon gas. The fibrous titanium oxide was synthesized from the supercritical sol-gel reaction using TIP. The supercritical sol-gel reaction using TBO precursor succeeded the titanium oxide mixed-crystal of anatase and rutile phases with the urchin-like morphology with a surface area of 63 m2 g−1.