Photocatalytic activity of ZnFe2O4/NiO nanocomposites carried out under UV irradiation

Abstract

The photocatalytic activity of zinc ferrite (ZnFe2O4) nanoparticles (NPs) is suppressed by the rapid recombination of the photogenerated electron-hole pair. Herein to achieve electron-hole separation, ZnFe2O4 was combined with nickel oxide (NiO) NPs to produce (1-x)ZnFe2O4/xNiO nanocomposites (NCs) with enhanced photocatalytic activity where the weight fraction (x) ranged between 0.1 and 0.5. The photocatalytic performance of ZnFe2O4/NiO NCs was evaluated in the degradation of nitrobenzene under UV irradiation at 254 nm and compared to the activity of pure ZnFe2O4 and NiO NPs. Phase purity tested by X-ray diffraction (XRD) confirmed the sole presence of ZnFe2O4 and NiO. The cubic shape with rounded edges morphology of the prepared samples was revealed in transmission electron microscopy (TEM). The specific surface area of ZnFe2O4/NiO NCs obtained by N2 adsorption-desorption isotherms ranged between 12 and 17 m2/g. The photocatalytic activity of pure NPs and NCs in the degradation of nitrobenzene under UV irradiation was also studied; maximum efficiency was achieved with the (1-x)ZnFe2O4/xNiO NCs where x = 0.3. This was due to the low recombination rate of electron-hole pairs confirmed by photoluminescence (PL) spectroscopy. Several other factors (catalyst dosage, pH and temperature) affecting the degradation efficiency were also investigated. The optimum experimental conditions were applied to identify the products of the degradation reaction. Comparison studies between the photocatalytic activity of ZnFe2O4/NiO NCs and ZnFe2O4/Mn2O3 NCs were reported.