Tuning SnO2-TiO2 tandem systems for dyes mineralization

Six SnO2-TiO2 tandem semiconductor samples were prepared by spray pyrolysis deposition using different precursor compositions and deposition temperatures. By tailoring the indium doped tin oxide layer (morphology, crystallinity) the tandem properties can be modified according to the targeted application, insuring enhanced charge separation, higher photosensitivity and reduced recombination. On the SnO2 layer, the TiO2 growth was proved to be almost twice faster when starting from halide precursor, compared to organo-metallic ones, at a fixed deposition temperature (400 degrees C). The samples were characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, contact angle, reflectance, current density-voltage (J-V) and photocurrent measurements. The photocatalytic efficiency of the tandem systems was tested on methylene blue reference solutions and was evaluated based on the variations in the organic carbon and total nitrogen content. The result were compared with bleaching measurements, showing that mineralization could be reached up to 90% and carbon removal is more efficient compared with nitrogen compounds. (C) 2013 Elsevier B.V. All rights reserved.