Synergistic effects of Fe–Mg co-doping in NiO nanoparticles for improving photocatalysis and dielectric response
摘要
The photocatalytic and dielectric responses of Fe–Mg co-doped NiO nanoparticles (NPs) prepared via a composite hydroxide-mediated route have been studied in detail. The successful formation of a pure cubic crystal structure of undoped and co-doped NiO NPs was verified by Rietveld refinement of XRD data. The average crystallite size decreased from 28 to 19 nm with co-doping due to the difference in ionic radii of co-dopant atoms. Transmission electron microscopy analysis using ImageJ software indicated the average particle size of about 82 nm for undoped NiO NPs. Fourier transform infrared spectra showed a characteristic Ni–O absorption band around 615–630 cm−1, further confirming the formation of desired molecular bonding. A decrease in optical bandgap from 3.77 to 3.54 eV with co-doping was observed due to the possible formation of sub-band states. A photodegradation experiment for MO dye showed a rapid and increased degradation rate with co-doping and the highest efficiency of 90.6% (in 60 min) was achieved, attributed to reduced electron–hole recombination caused by the co-dopants. Frequency-dependent dielectric measurements showed an increase in dielectric constant and AC conductivity due to increased polarization phenomenon and charge concentration by co-doping. Cole–Cole relaxation model fitting indicated decreased relaxation time and a non-Debye relaxation phenomenon in these NPs samples.