Frequency and temperature dependence of dielectric permittivity/electric modulus, and efficient photocatalytic action of Fe-doped CeO2 NPs

Abstract

A simple chemical precipitation route was employed to prepare Fe-doped CeO2 nanoparticles and the samples were verified by XRD, FESEM, XPS, Raman, UV–visible, PL, VSM and impedance analyses. Cubic fluorite structure of CeO2 and Fe-doped CeO2 nanoparticles was confirmed by X-ray diffraction data/patterns. SEM images evidenced the formation of nanoparticles with spherical morphology. Raman and X-ray photoelectron spectroscopic studies were performed to quantify the microstructure and chemical state of atomic species of samples. The dielectric permittivity and electric modulus of prepared materials were recorded in temperature range 293–393 K and frequency range 120 Hz–100 kHz. The ε′(f) and ε˝(f) plots exhibit two different regions namely a dielectric dispersion region at low frequency and a plateau region at high frequency. Electric modulus demonstrated the electrical relaxation behavior of prepared nanosized particles. The M-H curves indicated that nanosized CeO2 and Fe-doped CeO2 particles possess room temperature ferromagnetic (RTFM) behavior with low retentivity and coercivity. Optical absorption edge shifted towards higher wavelength with Fe increment and indicated a decrease in optical band gap from 3.33 to 3.05 eV. Photocatalytic action of prepared CeO2 and Fe-doped CeO2 nanoparticles was evaluated by degrading MB dye solution under visible light irradiation. 4% Fe-doped CeO2 nanoparticles exhibited a higher photocatalytic activity (97.2%) compared with CeO2 NPs, which is attributed to decrease in optical band gap and increase in specific surface area. In addition, Fe-doped CeO2 nanoparticles provided an evidence of high quality photocatalytic performance against organic dyes during waste water treatment for environmental remediation.