Tailoring the optical parameters of CuO nanoparticles via Ni and Co co-doping

Abstract

In this study, we describe the preparation of Ni and Co co-doped CuO nanoparticles (NPs) with different weight ratios (2, 4, and 6 wt% of Ni and Co) via electrochemical deposition in the galvanostatic regime. We investigated the structure, morphology and optical properties of the NPs using X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffuse reflectance spectroscopy (DRS). The energy band gap exhibited blue and red shifts with increasing Ni and Co doping levels, respectively. The optical constants were calculated using the Kramers–Kronig method. The multiple peaks observed in the n, k, ε₁, and ε₂ spectra may be due to different NPs interacting with the photon. The refractive index versus wavelength decreased with increasing Ni and Co doping levels, while the extinction coefficient exhibited similar behavior for all NPs.