Enhanced electrochemical and optical properties of polyaniline-based Ag2O/NiO/ reduced carbon black nanocomposites for renewable energy applications

Abstract A multi-step synthesis strategy was employed to fabricate Ag 2 O/NiO/rOCB@PANI core-shell nanocomposites. Silver oxide and nickel oxide nanoparticles were first decorated onto a reduced oxidized carbon black matrix (Ag/Ni/rOCB hybrid core), followed by the in situ polymeric encapsulation of this core within a protective, conductive polyaniline (PANI) shell, assessing their electrochemical, dielectric, and optical properties for potential applications in renewable energy applications. Structural and spectroscopic analyses, including FTIR, Raman spectroscopy, XRD, SEM/EDAX, and TEM, confirm the successful formation of conductive Ag 2 O/NiO/roCB@ PANi nanocomposites. The electrochemical behavior of the Ag 2 O/NiO/roCB@ PANi composite was investigated using cyclic voltammetry (CV) measurements which identified distinct oxidation and reduction peaks, offering valuable insights into redox behavior. Electrochemical impedance spectra EIS has shown a low charge transfer resistance (Rct), indicating efficient electron transfer at the electrode/electrolyte interface, which are suitable for hydrogen evolution reaction HER. The combined CV and EIS results establish a stronger correlation between the structure of the composite and its electrochemical behavior. The observed enhancement is attributed to the combined contributions of the electroactive PANI matrix, Ag 2 O/NiO components, and the highly conductive roCB, which together promote efficient charge transport and interfacial redox activity. The dielectric study highlights a strong frequency-dependent variation in the dielectric constant (ε′), demonstrating enhanced charge storage capacity and interfacial polarization due to Ag 2 O/NiO/roCB doping. Ac conductivity measurements of the prepared nanocomposites showed high ac conductivity reaching up to 5.21*1 0 − 1 S/cm − 1 . AC conductivity (σ ac ) follows the correlated barrier hopping (CBH) model, indicating improved charge transport and conductivity. Moreover, fluorescence microscopy (FM) has been used to track the optical characteristics of the produced nanocomposites after they are exposed to various lights of different wavelengths. The FM results revealed that the nanocomposites emit fluorescent lights upon irradiation by red, green and blue lights. This suggests that the produced nanocomposites contain fluorophores that are both light-absorbing and capable of longer-wavelength light reemission. These characteristics support their application in LEDs, solar cells, and electronic devices. The findings suggest that Ag 2 O/NiO/roCB@ PANi composites possess promising electrochemical and optical properties, making them viable materials for hydrogen evolution reaction (HER) and renewable energy technologies. As far as we know, no one in the field of electrochemistry has ever created such composites in terms of their preparation method and unique electro catalytical and optical properties.