A simple ball milling method for the preparation of p-CuO/n-ZnO nanocomposite photocatalysts with high photocatalytic activity.

The p-n junction photocatalyst, p-CuO/n-ZnO, was prepared via ball milling of ZnO and CuO nanoparticles in water. The structural, optical, and surface properties of the p-n junction photocatalyst p-CuO/n-ZnO were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis spectroscopy, and Zeta potential analyzer. The Photocatalytic activity of the photocatalyst was evaluated via photocatalytic oxidation of Methylene Blue (MB) in the presence of UV light. This study demonstrates a novel p-n junction oxide photocatalyst p-CuO (wt. 10%)/n-ZnO having superior photocatalytic activity (PCA) for the degradation of model dye under the illumination of UV-Vis light. The MB solution was only PCA, degraded by 100% within 15 min by the use of CuO (wt. 10%)/ZnO photocatalyst. Effectivley 365% increase in degradation rate constant was noticed for CuO (10 Wt.%)/ZnO nanocomposite as compared to that of pure ZnO nanoparticles. The enhanced PCA is anticipated from the presence of many micro p-n junctions formed between ZnO-CuO nanoparticles upon ball milling, which helps in efficient electron/hole pair charge separation upon excitation. The study highlights the fact that PCA of p-n junction CuO/ZnO photocatalyst can be effectively tuned by manipulating the interface of the heterostructure and by adjusting the parameters affecting the PCA. The result obtained from PCA is further verified by the zeta potential study.