Anatase titania nanorods by pseudo-inorganic templating

Abstract

A novel, facile and cost-effective single step aqueous sol–gel method for the synthesis of anatase TiO2 nanorods without the assistance of structure-directing organic/inorganic templates is reported. We specifically demonstrate a pseudo-inorganic templating method using ammonium iron (III) sulfate. Highly thermal stable anatase TiO2 nanorods were obtained using titanium oxysulfate and ammonium iron (III) sulfate as precursors. The structural, microstructural and chemical analyses of the nanorods synthesized, strongly supported the pseudo inorganic templating role of ammonium iron (III) sulfate on the formation of nanorod morphology. The materials have been characterized using different techniques such as TEM, XRD, BET surface area measurement, diffuse reflectance spectra and XPS. TEM study confirmed the rod shape of nano-anatase TiO2, having a diameter in the range of 20–40nm and a length of 100nm. XPS investigation showed that along with Fe3+, nitrogen and sulfur were also been doped into the TiO2 lattice from the single source dopant precursor ammonium iron (III) sulfate. Moreover, UV/vis diffuse reflectance spectra of nanorods showed red-shifts towards visible light and a corresponding decrease in band-gap energies consistent with an n-type doping of the anatase TiO2 matrix. This aqueous sol–gel synthesis of anatase nanorod with pseudo inorganic templating explores the advantages of inexpensive precursors, control over the powder morphology and optical properties, and distribution of the dopants over TiO2 at nano level due to homogeneous mixing of the precursors. Finally the photocatalytic analysis showed that the TiO2 nanorod have two times higher activity than the commercially available Degussa P 25.