Elaboration, characterization and applications of SnO2, 2 %Gd-SnO2 and 2 %Gd-9 %F-SnO2 thin films for the photocatalytic degradation of MB by USP method

Abstract

• An investigation on SnO 2 , 2 %Gd-SnO 2 and 2 %Gd-9 %F-SnO 2 thin films have been synthesized by USP method. • Effect of doping and co-doping on the structrales, microdtructurales, optical and electrical properties of SnO 2 thin films. • The development of the parameters: lattice parameters, average crystalline sizes, Seeback coefficient and energy gap with doping and co-doping are discussif. • The photocatalytic degradation of methylene blue was studied using 2 %Gd-SnO 2 and 2 %Gd-9 %F-SnO 2 thin films. In this study, SnO 2 , 2 %Gd-SnO 2 , and 2 %Gd-9 %F-SnO 2 films were grown from tin chloride solutions by the ultrasonic spray technique on ordinary microscope glass substrates heated to a fixed temperature of 450 °C for photocatalytic application. The microstructural characterization of the thin films obtained was performed using X-ray diffraction (XRD), SEM, EDAX, and Infrared Spectroscopy (IR). The optical properties of thin films were studied by UV–Visible spectroscopy. To examine the electrical properties, we use the four-point method, the Seebeck effect and the Mott Shottky analysis. X-ray difraction reveals the formation of the routile phase of SnO 2 in all thin films with average crystallite size estimated in the range of 24–62 nm. The co-doping in (Gd-F) permitted an improvement of the thermoelectric properties of SnO 2 . Moreover, we have demonstrated that an increase in grain size allows toimprove the Seebeck coefficient, to increase the electrical conductivity, on the other hand the doping in (Gd), presents a decrease in the size of the crystallites, which improves the degradation of methyl blue. The UV–Visible spectra of optical transmission of the layers show that the pure, doped and co-doped SnO2 films are of good quality with a transmittance of 73–83% in the visible and have an optical gap evaluated between 3.89, 3.98 and 3.99 eV respectively.