Structural, electrical and photoluminescence properties of ZTO thin films for water depollution

Graphical abstract of electron transfer and degradation mecahanism. • Azo dye Black Amido (BA) should not be discharged into effluents and natural sources without prior treatments for a partial or total elimination. • To attain this aim, the optimized ZTO thin film are suggested to be used as a photo-catalyst for the BA degradation. • The result shown that ZTO film could be used as a stable photo-catalyst for the photo-catalytic application. The degradation of an azo dye Amido Black 10B in aqueous solution by photo-catalytic reaction with an optimized ZnO-SnO 2 (ZTO) thin film has been investigated. Optimization of structural, electrical and photoluminescence properties of ZTO films was carried out by varying the molar ratio (ZnO:SnO 2 ) from (1:1) to (4:1) during the chemical sol–gel deposition. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Hall Effect measurements, UV–Visible analyzes, and photoluminescence spectroscopy (PL). SEM analyzes confirm the synthesis of ZTO layers and indicate that the morphology of the obtained ZTO layers change by increasing the molar ratio. XRD shows a slight increase in the crystalline nature of ZnO and a small decline in that of SnO 2 by increasing the concentration of ZnO. The results of Hall effect measurements, photoluminescence spectroscopy and UV–Vis analyzes suggest that the optimized addition of the ZnO improve light absorption especially in the short wavelength range and participate in radiative recombination under photo-excitation. Evolution of the photo-catalytic activity revealed that the optimized ZTO thin film exhibited an improved photo-catalytic performance in the degradation of Amido Black 10B under UV irradiation. Around 70.46% of the degradation of this azo dye was achieved within 240 min. These results suggest that prepared ZTO with molar ratio of (2:1) is promising candidate for photo-catalytic application.