Synthesis and characterization of NiO and NiO-CdO nanocomposite photocatalysts

In this research, a NiO-CdO nanocomposite photocatalyst was synthesized by a sol-gel method. The synthesized samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), diffuse reflectance spectroscopy (DRS) and ultraviolet-visible (UV-vis) spectroscopy. XRD results showed the formation of NiO and CdO phases without the presence of other impure phases in the nanocomposite. The photocatalytic properties of the synthesized nano composite was then compared with NiO powder. FESEM results demonstrated that the particle size in the nanocomposite sample was in a range of ۲۰ to ۳۰۰ nm, while for the NiO sample the average particle size was about ۴۰ nm. According to the DRS results, the band gap energies for NiO and NiO-CdO nanocomposite samples were ۲.۹ and ۲.۶ eV, respectively. Photocatalytic activity of both samples were compared in degradation of methylene blue (MB) dye under visible light irradiation. The degradation of the nanocomposite sample halved after ۱۸۰ min, which was about ۳ times the NiO sample was degraded. Finally, kinetic analysis of the photocatalytic degradation reaction for two samples were performed and compared.

Keywords:

Photocatalyst , Nanocomposite , NiO-CdO , NiO , Methylene blue