Synthesis and characterization of Ni-doped α-Fe_2O_3 nanoparticles through co-precipitation method with enhanced photocatalytic activities

摘要

Abstract In the present study, an attempt has been made for synthesis, characterization and photocatalytic application of pure and Ni-doped α-Fe~(2)O~(3)(hematite) nanoparticles by chemical co-precipitation method. The synthesized products have been studied by Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FT-IR), Raman spectroscopy, Ultraviolet–Visible (UV–Vis) analysis and Vibrating Sample Magnetometer (VSM). The TGA showed three mass losses, whereas DTA resulted in three endothermic peaks. XRD measurements confirm that all the prepared nanocrystals consist only in nanocrystalline hematite phase. TEM and SEM show that the size of the nanoparticles decreases with Ni-doping. FTIR and Raman spectroscopies confirm the phase purity and the phonon modes of the synthesized nanoparticles. The UV–Vis absorption measurements confirm that the decrease of particle size is accompanied by a decrease in the band gap value from 2.02 eV for α-Fe~(2)O~(3)down to 1.81 eV for 8 mol% Ni-doped α-Fe~(2)O~(3). Furthermore, the magnetic properties demonstrated that all of the samples exhibited ferromagnetic behavior at room temperature. On the other part, the photocatalytic activity of Ni-doped α-Fe~(2)O~(3)particles was studied using methylene blue (MB) as model organic pollutants. The 8 mol% Ni-doped α-Fe~(2)O~(3)nanoparticles disclosed that the discoloration of MB reached 86% after irradiation of 140 min.