Effect of Cu substitution on morphological optical and electrochemical properties of Co3O4 nanoparticles by co-precipitation method

In this present study, pure Co₃O₄ and Cu-substituted Co₃O₄ nanoparticles (NPs) were prepared by a simple co-precipitation method and their structural, morphological, optical, and electrochemical properties were assessed. X-ray diffraction (XRD) analysis indicated that the synthesized samples had a cubic structure with the formation of a secondary phase (CuO) was detected at a higher Cu concentration. The average crystallite was decreased with increasing Cu content. Fourier transform infra-red (FT-IR) analysis revealed that the presence of vibrational bands in Cu-substituted Co₃O₄ NPs. The morphological study of the pure Co₃O₄ and Cu-substituted Co₃O₄ NPs revealed that the hexagonal structure with porous morphology confirmed by Field emission scanning electron microscopy (FESEM). High resolution transmission electron microscope (HR-TEM) analysis with spotty diffraction rings showed that pure Co₃O₄ and Cu-substituted Co₃O₄ NPs were polycrystalline in nature. The optical properties of synthesized samples exhibited strong absorption edges, and bandgap values were found to be increased from 3.60 to 3.75 eV. Cyclic voltammetry (CV) was employed to investigate the electrochemical properties of the synthesized materials. The CV curves exhibited pseudocapacitive behavior, and 2 % Cu substituted Co₃O₄ electrode had a high higher specific capacitance value than pure Co₃O₄ electrode.