Synthesis and characterization of Zn-doped α-Fe2O3 nanoparticles with enhanced photocatalytic activities

Abstract

In present work, the optical, magnetic and photocatalytic properties of undoped and Zn doped α-Fe2O3 nanoparticles was investigated intensively. The Zn doped hematite nanoparticles were synthesized by simple co-precipitation method, changing the molar ratio of zinc precursors. The obtained photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infra-red (FTIR), Raman spectroscopy, diffuse reflectance UV–visible spectroscopy (DRS) and vibrating sample magnetometer (VSM). The structural properties showed that the obtained nanoparticles are single phase rhombohedral (hexagonal) structure with the space group R-3c in all compounds. TEM and SEM results show that the size of the nanocrystals decreases with Zn-doping down to 21 nm. Raman spectroscopy was also used for confirming zinc atoms replacing iron position in Zn doped α-Fe2O3 crystal. The energy gap decreased gradually by increasing the doping concentration of zinc. The specific saturation magnetization (Ms) of the nanoparticles was measured at room temperature. The magnetic parameter of Ms, was found to decrease with the increase in Zn concentration. Zinc doped α-Fe2O3 showed the enhanced photocatalytic properties within photodegradation of methyl orange (MO). The 6% Zn-doped α-Fe2O3 nanoparticles showed the highest photocatalytic activity and led to an almost complete discoloration of MO solutions, i.e. 87.4% at pH = 4 after UV–visible irradiation of 140 min.