Structural, Optical, and Electrochemical Behavior for Different Levels of Nickel and Copper Co-Doped CdO Nanoparticles

Cadmium oxide (CdO) nanocrystals were synthesized in co-doped form using a simple chemical precipitation method. Constant-weight copper (1.34 wt.%) and varying-weight (0.44 wt.%, 0.88 wt.%, 1.32 wt.%, 1.76 wt.%, and 2.2 wt.%) nickel co-doped CdO nanomaterials were incorporated. The materials were prepared and subsequently annealed at 550°C. The synthesized samples were evaluated for their structural, optical, and morphological properties. According to diffraction studies, CdO has a cubic structure in the pure phase. The UV-Vis absorption spectra showed that all the doped products exhibited a red shift. They also indicated that the bandgap of the host material doped with a low nickel concentration decreased. Furthermore, photoluminescence spectroscopy revealed three very intense emission peaks caused by nickel doping in the visible light region. The sample morphology was investigated and verified using field-emission scanning electron microscopy (FESEM) analysis and high-resolution transmission electron microscopy (HRTEM). The electrochemical capacitance behaviors of Cdo:Cu (1.34 wt.%) + Ni (0.88 wt.%), Cdo:Cu (1.34 wt.%) + Ni (1.32 wt.%), and Cdo:Cu (1.34 wt.%) + Ni (2.2 wt.%) were investigated using cyclic voltammetry. At a low scan rate of 10 mV/s, the electrode of Cdo:Cu (1.34 wt.%) + Ni (0.88 wt.%) provided a capacitance of 201 F/g, whereas the capacitance of CdO:Cu (1.34 wt.%) + Ni (1.32 wt.%) increased to 233 F/g. Graphical Abstract