NiO Coupled ZnO Nanoparticles: Preparation, Characterization and their UV-Vis Photocatalytic Activities

Nanostructured metal oxides ZnO, NiO and their coupled oxides in the molar ratio 1:1, 2:1 and 1:2 (labeled as ZnNi, Zn2Ni and ZnNi2, respectively) were successfully synthesized by a one-step microwave assisted solution combustion process. As-prepared nano metal oxides were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). The optical absorption of ZnO could be extended into the visible region after the loading of NiO and the coupled metal oxide, Zn2Ni showed a band gap of 2.95 eV. The coupled metal oxide, Zn2Ni exhibited excellent photocatalytic efficiency towards the degradation of 2,4-dichlorophenol, under UV and visible light irradiation, when compared to individual ZnO, NiO and the other coupled oxides due to the efficient separation of photogenerated electron-hole pairs.