Investigation of mesoporous and microporous nanocrystalline silicon-doped titania

Abstract

A series of silicon-doped mesoporous and microporous nanocrystalline titanium dioxides were prepared by a new sol–gel technique in non-aqueous medium. XRD studies of the silicon-doped nanocrystalline titanium dioxide show a significant inhibition of anatase to rutile phase transition, comparing with both bulk and nanocrystalline values of pure titania. The phase transition temperature of the anatase to rutile is sensitively related to the silicon content. The results of XRD and TEM reveal that pure titanium dioxide nano-particles show a rapid increasing of the grain growth, accompanied by the phase transformation of anatase to rutile when calcined at 600–700 °C, while the grain growth of doped specimens was drastically arrested. As a result of heavy restraint of the grain growth, the silicon doped titania nano-particles show much higher surface area than that of pure titanium dioxide when heated by using the same heating program. Pure titania samples only exhibit mesoporous structure at the calcinations temperature range of 390–500 °C. However, the mesopores of doped materials exhibit significant thermal stability. When the silicon content is increased the ink-bottle mesopores are transformed to cylindrical micropores.