Ni and NiFe nanostructures anchored on a carbonaceous matrix for enhanced oxygen reduction reaction

Developing sustainable and efficient electrocatalysts for the oxygen reduction reaction (ORR) is essential for advancing clean energy technologies. Here, we report the hydrothermal synthesis, structural characterization, and electrocatalytic performance of novel Ni and Ni–Fe hybrid materials derived from 4-aminophenol ligands. Under eco-friendly hydrothermal conditions, the ligands polymerize to form a N/O-rich carbonaceous matrix with abundant hydroxyl (–OH) and amine/imine (–NH₂/–C N–) functionalities, serving as anchoring sites for metal incorporation. The electrochemical properties of fabricated electrodes containing different concentrations of the synthesized materials were investigated in acidic solutions. When both Ni and Fe were incorporated, FeOx or Ni–Fe mixed oxyhydroxide nanostructure were stabilized within the polymer matrix. Using a 50% NiFe composition, a maximum exchange current density of 1.82 mA/cm² was achieved. This remarkable performance can be attributed to the synergistic interactions between Ni and Fe, which enhance the density of active sites and improve oxygen adsorption and electron transfer, although partial pore blockage slightly reduces surface area. Moreover, cyclic stability analysis over 1000 cycles revealed an outstanding retention of 98.7%, highlighting the structural robustness of the hybrid material. These results indicate that 4-aminophenol-derived hybrid matrices provide an effective scaffold for designing high-performance ORR electrocatalysts, combining mesoporosity, strong metal–support interactions, and tunable mixed-metal active sites for sustainable energy conversion applications.