Construction of iron-nickel metal-organic framework anchored on reduced graphene oxide for enhanced oxygen evolution reaction electrocatalysis

Transition metals in elevated valence states are crucial for providing active sites in the oxygen evolution reaction (OER). However, their formation is challenging due to high energy barriers and instability. This study presents a novel bimetallic Fe-Ni metal-organic framework (MOF) anchored on reduced graphene oxide (rGO), achieving one of the lowest reported overpotentials for OER in this material class. The rGO@Ni₈₀Fe₂₀ MOF nanostructure is synthesized via a solvothermal method, and its formation is confirmed using various characterization techniques. The rGO@Ni₈₀Fe₂₀ MOF nanostructure exhibits excellent OER performance, requiring an overpotential of 217 mV at 10 mA cm⁻² while maintaining crystalline stability. It also maintains stable catalytic activity for over 100 h with a 16.1% decrease in current density. Compared to single-metal Fe or Ni MOFs, the bimetallic Fe-Ni MOF shows significantly enhanced performance due to the synergistic effect between the two metals. The stronger Fe-O bond facilitates efficient proton and electron transfer, accelerating the oxygen production reaction rate. Additionally, the interaction between the rGO structure and the MOF matrix enhances catalytic activity. Density functional theory (DFT) calculations reveal strong Fe-O bonding and electron density accumulation, contributing to enhanced electrocatalytic performance. This bimetallic structure also improves conductivity, offering insights for next-generation electrocatalysts in hydrogen economy applications.