A study on synthesis of an advanced electrocatalyst based on high-conductive carbon nanofibers shelled NiFe₂O₄ nanorods for oxygen evolution reaction

The selection and development of suitable electrocatalyst materials for the oxygen evolution reaction (OER) remain significant challenges, particularly in achieving objectives such as low overpotential, high durability, cost-effectiveness, abundant terrestrial availability, and scalability. So far, NiFe₂O₄ has been recognized for its superior catalyst properties compared to individual components like spinel Fe₃O₄ and cubic NiO, However, its performance gradually deteriorates over time, likely due to its amorphous nature and low intrinsic conductivity. In this study, carbon nanofibers (CNFs) were utilized to fabricate CNFs@NiFe₂O₄ nanorods through the facial methods, showing a conductive network that improves the overall conductivity of the catalyst material and facilitates the electron transfer process, driving down the overpotential. Notably, direct, and robust/solid bonds were established between CNFs and numerous NiFe₂O₄ nanorods, each possessing the major oxidation states of +2 and +3 for Ni and Fe, respectively, simultaneously emphasizing the synergistic influence arising from the interaction within the as-hybrid catalyst. Additionally, the arrangement of uniformly nanorods arrayed CNFs substrate as a unique configuration, providing an abundance of active sites for water adsorption, leading to decrease the reaction activation energy barrier, giving an accelerated kinetic reaction and efficient O₂ conversion. As a result, CNFs@NiFe₂O₄ catalyst demonstrated enhanced conductivity and electron transfer, reducing the overpotential to 277 mV at 10 mA/cm² and achieving a Tafel slope of 74.9 mV/dec during OER testing in 1.0 M KOH electrolyte. These findings address critical challenges associated with electrocatalyst materials, underscoring the potential of CNFs@NiFe₂O₄ in advancing efficient and stable OER processes.