Effect of tantalum addition on anatase phase stability and photoactivity of aqueous sol-gel derived mesoporous titania

The effect of the addition of tantalum to nanocrystalline titania matrix on the photocatalytic activity is presented. The tantalum addition increases the anatase phase stability to above 1000 degrees C by inhibiting the increase in crystallite size of titania. All the tantalum added titania compositions have higher surface area than pure titania. Transmission electron micrograph images support the reduction in crystallite size of titanium oxide in presence of tantalum. Addition of tantalum above I mole percentage increases photocatalytic activity considerably and the activity is much higher than that of commercially available Hombikat UV 100 titania. All the compositions containing tantalum have higher photoactivity than pure titania. The synergistic effect of high surface area and small crystallite size is found to be responsible for the observed photocatalytic activity rates. The aqueous sol-gel method adopted for the preparation of tantalum added titania from cheaper salt precursors and the resultant highly photoactive titania make this investigation promising for various technological applications. (c) 2007 Elsevier B.V. All rights reserved.