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 ZnOMgO 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 - 11.449x10^{11 -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.