Structural And Optical Properties of (NiZnO/rGO) Nanocomposites

Lavanya G, Suvarna T and Vardhani CP

Published on: 2023-07-12

Abstract

Nickel-Zinc oxide/Reduced Graphene Oxide (NiZnO/rGO) nanocomposites have been successfully synthesized by the Co-precipitation process .Obtained materials were characterized by the X-ray diffraction (XRD) confirmed the average crystallite sizes of the nanopowders are less than 100 nm. Peak broadening indicates that the smaller crystallites size of the prepared NiZnO/rGO nanocomposites. The structural examinations using X-ray diffraction (XRD) exposed the hexagonal wurtzite structure in both pure and Ni doped ZnO/rGO samples. The presence of an additional secondary phase accredited to NiO was also observed in Ni doped sample. The micro structural investigations using Field emission scanning electron microscope (FESEM) revealed that Ni addition in ZnO/rGO depicts that the particles are uniform in size and they are in agglomeration and the elemental analysis is confirmed by Energy dispersive X-ray analysis (EDAX) shows four strong peaks correspond to carbon (C), oxygen (O), zinc (Zn) and nickel (Ni) with different weight percentages by doping Ni at different compositions. Fourier transform infrared spectroscopy analysis the formation of the Zinc oxide and the doping of nickel .The strong bands located at ~507 cm⁻¹ indicate the stretching vibration mode of Ni–O and Zn–O, respectively, which confirm the formation of NiZnO/rGO nano composites. The optical properties of the prepared NiZnO/rGO samples are characterized by the UV-visible absorption to determine the band gap of the metal oxide nanocomposites. It can be seen in all the spectra that the strong absorption peaks were appeared at around 350nm, which is attributed to the band gap absorption in NiZnO/rGO nanocomposites. The calculated values of the band gap energies of NiZnO/rGO nanocomposites are 3.50, 3.49, 3.47 and 3.48eV respectively, at wavelengths 353.4nm, 354.5nm, 356.8nm and 355.7nm which are good agreement with reported band gap values of NiZnO nanocomposites. Band gap energy of NiZnO/rGO nanocomposites is decreased owing to induction of strain in crystal lattice. Photoluminescence results disclosed that high concentrations of Ni⁺² ions in NiZnO/rGO nanocomposites improve distortion centers and lattice surface defects in ZnO and as a consequence that minimizes defect related emissions. A red shift in the band gap has been observed from the room temperature optical absorption and PL spectra of nickel doped ZnO nanoparticles. Such a red shift in band gap may be attributed to the sp–d exchange interactions between the band electrons and the localized d electrons of the Ni⁺² ions substituting Zn ions clearly indicating the incorporation of Ni ions into the Zn site of the ZnO lattice. NiZnO/rGO nanocomposites are mainly applicable in various electrical, optoelectronic and photo catalytic applications. In the present study, NiZnO/rGO nanocomposites with different Ni compositions was prepared by Co-precipitation method .Crystalline structure, morphology and optical properties were investigated and discussed according to the experimental results.