CuO-ZnO nanocomposites-based thin films: Characterization, physical properties and sunlight photocatalytic degradation of organic pollutants

One of the most commonly employed techniques for boosting photocatalytic efficiency by separating photo-induced electrons and holes is the formation of heterojunctions. The photocatalytic activity of CuO-ZnO nanocomposites-based thin films was investigated in this work for the decomposition of a model pollutant, methylene blue (MB), under sunlight irradiation. The spray pyrolysis method was utilized to produce nano-sized pure CuO and ZnO thin films, as well as CuO-ZnO nanocomposite thin films with varied molar ratios (Cu:Zn 1:3, 1:1, and 3:1). The structural and optical properties of the prepared materials were carefully studied. Contact angle measurements were used to determine the samples' wetting properties. XRD and Raman spectra confirmed the hexagonal würtzite and cubic structures of ZnO and CuO crystals in the different heterostructures. SEM images demonstrated the growth and distribution of the grains, with some spherical or plate-like nanostructures. The composition of the synthesized nanocomposites is confirmed by EDX analysis. UV-Vis investigations indicate that the optical band gaps are considerably impacted by the composition of nanocomposites. PL measurements confirmed a large number of defects in the synthesized nanocatalysts. These data also reveal that the formation of p-n heterojunctions prevented photogenerated carriers from recombining. The photocatalytic activity of the prepared CuO-ZnO nanocomposites was found to be greater than that of individual semiconductors. A possible mechanism and involvement of radicals in photocatalytic dye degradation were also proposed. As a result, the produced nanocomposite thin films might be beneficial for environmentally friendly and energy-saving wastewater treatment.