Synthesis Temperature Dependent Morphological Evolution in Zinc Titanate Heteronanostructures and Their Application in Environmental Remediation

The synthesis of Zn-Ti glycolates at different temperatures (RT to 200 degrees C) with different morphologies which convert to zinc titanate heteronanostructures after calcination (500/700 degrees C) has been reported. The effect of synthesis temperature on morphology, optical properties and photocatalytic activity of the heteronanostructures has been investigated. X-ray diffraction studies indicate that after calcination, cubic ZnTiO3 is formed from the Zn-Ti glycolates synthesized at lower temperatures (<= 100 degrees C) while Zn2TiO4 is formed at higher temperatures (> 100 degrees C). Electron microscopy studies show that the Zn-Ti glycolates synthesized at lower temperatures (<= 100 degrees C) and the corresponding zinc titanates exhibit rod-like morphology. The Zn-Ti glycolate synthesized at 150 degrees C and the corresponding zinc titanate possess mixture of rod and spherical morphology. The Zn-Ti glycolates synthesized at 180 and 200 degrees C and the zinc titanates exhibit spherical morphology. The rods and spheres were found to be formed in turn by assembly of nanoparticles. Diffuse reflectance spectroscopic studies show that the band gap of zinc titanates (3.2 eV to 3.75 eV) depends on synthesis temperature of Zn-Ti glycolates and also the calcination temperature. The zinc titanate heteronanostructures were explored as catalysts for the photodegradation of rhodamine B and crystal violet in aqueous solutions in the presence of sunlight and the zinc titanate spheres exhibit the best catalytic activity.