Electrodeposition of Binary ZnO-MgO Nanocomposite Thin Films: Influence of pH Bath on Microstructural and Optical Properties

Abstract

The article examines the influence of pH bath on microstructure and optical properties of nanocomposite thin films of ZnO-MgO films. These films were fabricated through potentiostatic electrodeposition on fluorine-doped tin oxide (FTO) coated glass substrates, utilizing a mixed electrolyte solution containing 40 mM (40%) Zn(NO₃)₂·6H₂O and 40 mM (60%) Mg(NO₃)₂·6H₂O. The resulting ZnO-MgO nanocomposites were characterized using optical spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) to analyze their structural and optical features. It was found that bath pH makes a large difference in the surface morphology, microstructural and optical characteristics. It shows that the thickness of the films increases between 341 - 451 nm and crystallite size of the film is reduced between 12.561 - 12.034 nm with pH value of 4.0, 5.0 and 6.0. The optical conductivity rose to 7.250 x1011 - 11.449 x1011 -1 Ω-1m-1 and the refractive index rose from 1.859 to 2.226, whereas the band gap and transmittance decreased from 3.28- 3.12 eV and 81- 56% respectively when the bath pH values rose.