Abstract

Polyaniline (PANI) is a conducting polymer that has gained attention as a matrix material for oxygen reduction reaction (ORR)
catalysts due to its high surface area, good electrical conductivity, and stability. In this comparative study, the electrochemical
properties of nickel oxide (NiO) and cobalt (II,III) oxide (Co3O4) catalysts, both embedded in a PANI matrix, were investigated
and compared for ORR. The NiO and Co3O4 catalysts were synthesized using a simple reduction method and embedded in
the PANI matrix through mechanical mixing. The synthesized catalysts were characterized using X-ray diffraction, Fourier-
transform infrared spectroscopy, and ultraviolet (UV)-visible spectroscopy. The electrochemical performance of the NiO/PANI
and Co3O4/PANI catalysts was evaluated using cyclic voltammetry and electrochemical impedance spectroscopy. The results
showed that NiO/PANI catalyst possessed slightly higher activity than the Co3O4/PANI catalyst. The stability of the catalysts
was also investigated from a cyclic voltammogram, where the catalysts were cycled between −0.7 V and 1.5 V for 100 cycles.
The results showed that the NiO/PANI and Co3O4/PANI catalysts both exhibited good stability. Overall, the comparative study
demonstrated that both NiO/PANI and Co3O4/PANI catalysts exhibited good electrocatalytic activity and stability for ORR. The
study also showed that the PANI matrix provided stable and conductive support for the catalysts. The results suggest that both
NiO and Co3O4, embedded in a PANI matrix, have the potential to be used as low-cost and efficient catalysts for ORR.