Abstract
In this work, copper-nickel oxide (Cu1-xNixO) thin films with varying nickel substitution ratios were prepared using spin coating route. The X-ray diffraction (XRD) results showed that all samples are polycrystalline nanostructure. Increasing substitution ratio led to a gradual convert from monoclinic CuO to the cubic NiO phase. Scanning electron microscopy (SEM) revealed porous structure of CuO film. Nickel addition reduced particle size, increased bonding, and decreased surface porosity. High nickel ratio films exhibited disc-shaped structures with nano dimensions. The EDX analysis indicated the low content of oxygen suggesting oxygen vacancies. FTIR spectroscopy showed characteristic bands for nanocrystalline copper oxide, with nickel substitution resulting in the emergence of broad bands corresponding to Ni-O vibrations. Optical absorption spectroscopy showed the absorption edge around 350 nm for all samples, with high transmittance up to 93% for nickel oxide in the visible range. The optical bandgap increased with nickel substitution from 3.90 eV for pure copper oxide to 3.98 eV for pure nickel oxide. The high transmittance and large surface area of Cu1-xNixO films make them ideal for use in gas sensors, photocatalysts, and as window materials in solar cells applications.