Photocatalytic efficiency of undoped and Cu-doped ZnO thin films coated inside transparent glass tube as one-piece photoreactor

• Synthesis of Cu-doped ZnO thin films by ultrasonic spray pyrolysis on glass, silicon and transparent tubes. • Investigation of copper effect on the properties and the photocatalytic performance of ZnO photocatalyst. • Copper substitution results in creation of structural defects and decrease of the crystalline size. • Copper doping reduces the recombination process (UV luminesce peak) and rises the visible luminescence. • The integration of the photocatalyst with photoreactor responds the separation issue. • The photoreactor configuration is of high performance and stability. In recent years, the contaminated rejects due to the rise of textile and dye industry have dramatically affected the ecosystem and aquatic reserves. In addition, the decontamination of organic species based on nanoparticles as photocatalyst is considered as a complicated route and material consumer. To address the separation issue, it is necessary to develop new methods to degrade organic dyes through coast effective processes. In this context, we present in our study a new photocatalysis design by implementation of the photocatalyst on the inner side surface of transparent glass tube as one piece-photoreactor. Among various Photocatalysis based on metal-oxide materials, zinc oxide is widely studied by tailoring its physical and chemical properties to improve the photocatalytic degradation activity. Accordingly, pure and Cu-doped ZnO catalysts with variable copper amount (1, 2.5 and 4 wt%) were synthesized by ultrasonic spray pyrolysis and characterized by X-ray diffraction (XRD), Raman spectroscopy, UV–visible spectroscopy, Photoluminescence spectroscopy (RT-PL), Atomic force microscopy (AFM), Scanning electron microscopy (SEM), Complex impedance spectroscopy and X-ray photoelectron spectroscopy (XPS). The methylene blue degradation rate was investigated through the decrease of the absorption band situated at 663nm under UV-Vis irradiation. The reusability of the undoped and Cu-doped ZnO photocatalyst tests after six recycles give a steady photodegradation efficiency results