Investigation on physical properties of CuO and SnO₂: F mixed oxide sprayed thin films for photocatalytic application: coupling effect between oxides

This article presents the synthesis and characterization of CuO–SnO₂: F mixed oxide thin films using the spray pyrolysis technique on glass substrates. The study focuses on optimizing the structural, optical, and electrical properties of the films by varying the molar ratios of copper and tin. X-ray diffraction analysis confirmed the polycrystalline nature of the films, with a combination of monoclinic CuO and tetragonal SnO₂ phases observed. AFM analysis show a remarkably rough surface with a pronounced roughness measuring approximately 150 nm. The band gap energy was found to vary from 3.95 to 3.57 eV as the molar ratio of tin decreased. The molar ratio also had a significant impact on the electrical properties of the films. Additionally, the photocatalytic activity of the optimized thin films was evaluated by measuring the degradation of MB dye under sunlight illumination. The results showed that the thin films prepared with a molar ratio of 75% copper exhibited higher photocatalytic activity compared to pure oxides. Furthermore, these films demonstrated higher stability after 5 cycles, with minimal changes observed in X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). We have shown that photocatalytic degradation of organic dye is better, by using mixed oxide system, than that for each oxide separately (SnO₂ and CuO). These findings suggest that the optimized CuO–SnO₂: F mixed oxide thin films have potential use in photocatalysis devices for industrial applications.