Optical properties analysis of gelatin-based prepared Co, Ni, and Mn-doped ZnO nanoparticles in infrared and UV-vis region using Kramers-Kronig methods

This study investigates the structural, optical, and morphological properties of ZnO nanoparticles doped with Ni, Mn, and Co (Zn 0.97 A 0.03 O where A = Ni, Mn, and Co, designated as ZN, ZM, and ZC, respectively). X-ray diffraction (XRD) analysis confirms the successful incorporation of dopants into the ZnO lattice without altering its wurtzite structure. Field emission scanning electron microscopy (FESEM) images reveal that doping results in larger and more uniformly distributed particles. Energy-dispersive X-ray spectroscopy (EDX) verifies the presence of Ni, Mn, and Co in the respective samples. Fourier transform infrared (FTIR) spectroscopy indicates an increase in average phonon energies due to doping, as evidenced by the shift in the Zn-O vibration peak. Ultraviolet-visible (UV-vis) spectroscopy shows that doping causes a blue shift in the absorbance peak and increases the optical band gap from 3.17 eV for pure ZnO to 3.22 eV for Co-doped ZnO. Transmission electron microscopy (TEM) and corresponding EDX results further confirm the presence of dopants and illustrate that doped ZnO nanoparticles are larger than pure ZnO particles. These findings provide valuable insights into the impact of doping on ZnO nanoparticles, potentially enhancing their suitability for various technological applications.