Hydrothermal synthesis of Ti oxide nanostructures and TiO2:SnO2 heterostructures applied to the photodegradation of rhodamine B

The present study describes the synthesis, characterization and testing of the photocatalytic potential of TiO2 nanoparticles (NPs), TiO2:SnO2 heterostructures and potassium titanate nanotubes (TNTs) obtained by the alkaline hydrothermal method. The materials were characterized by X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy, surface area estimated from the N-2 physisorption isotherm (BET), X-ray absorption near-edge structure (XANES) spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM) and Fourier transform near-infrared (FT-NIR) spectroscopy, among other methods. Photocatalytic potential was assessed by rhodamine B dye photodegradation under UVC radiation. The properties of the materials were shown to depend on the KOH concentration. Potassium TNTs with high surface area were obtained only in 5 mol L-1 KOH. The material composed of TiO2 anatase phase, which was obtained in KOH solution ranging from 10(-4) to 1 mol L-1, showed higher photocatalytic activity than the TNTs, despite the lower surface area and lower density of hydroxyl groups on the anatase. In the heterostructure syntheses, SnO2 NPs were identified attached to TiO2 when 10(-4) and 10(-2) mol L-1 KOH were used, whereas at [KOH] = 1 and 5 mol L-1, Sn remained in solution during the synthetic process and only the respective TiO2 phase was identified. The TiO2:SnO2 heterostructures were more active than the material without SnO2 prepared at the same KOH concentrations. (C) 2012 Elsevier B.V. All rights reserved.