Unraveling the effect of Gd doping on the structure, optical, magnetic, dielectric and photocatalytic properties of ZrO2 nanostructures

Nanocrystalline Zr1-xGdxO2 (0 <= x <= 0.20) samples were synthesized through the sol-gel combustion process and characterized by various characterization techniques. XRD analysis confirms a highly crystalline tetragonal phase with P42/nmc space group. TEM micrographs exhibit reduction in particle size on Gd doping. FTIR spectra ensure bending/stretching vibrational modes associated with the functional groups at different wavenumbers. Raman spectroscopy analyses reaffirm that the Gd doping does not affect the tetragonal phase of ZrO2 nanoparticles, signifying an excellent way to control the recombination rate of electron-hole pair. XPS analysis ensures the successful incorporation of Gd in the ZrO2 lattice. Room temperature magnetic measurements reveal the ferromagnetic nature of all the samples. The UV-visible spectroscopy shows increase in band gap from 3.82 eV to 4.45 eV. The dielectric constant varies significantly for the Gd-doped samples. All the prepared catalysts were tested for the photocatalytic activity of the methylene blue (MB) dye under visible light irradiation. After 120 min, 20% Gd-doped ZrO2 displays similar to 91% degradation efficiency against the MB dye, which makes it a promising visible light-activated photocatalyst.