Structural, optical, photoluminescence and sunlight photocatalytic properties of sprayed NiO-ZnO nanocomposite thin films

In this study, the photocatalytic properties of NiO-ZnO nanocomposite thin films were explored towards the degradation of a pollutant model, methylene blue, when exposed to sunlight. The spray pyrolysis technique was used to synthesize nano-sized pristine ZnO and NiO, as well as NiO-ZnO nanocomposites with different molar ratios (Ni:Zn 1:3, 1:1, 3:1). The as-prepared materials' structural and optical characteristics were investigated using different techniques such as XRD, Raman, EDX, SEM, photoluminescence, and UV–visible spectroscopy. The wetting properties of the samples were evaluated using contact angle measurements. The deposited NiO-ZnO nanocomposites were shown to have higher photocatalytic activity than the individual semiconductors. The enhanced activity of nanocomposites might be due to improved charge separation and the existence of oxygen vacancy, which capture these charges to produce active radicals after interacting with adsorbed oxygen. The inherent correlations between photocatalytic activities and PL intensities were investigated in depth.