Interfacial engineering and MOF-derived synthesis of Fe-doped Ni9S8/N-rGO for the oxygen evolution reaction

MOF-derived Fe-doped Ni 9 S 8 nanoparticles are uniformly anchored on N-rGO. • The synergistic effect at the heterointerface enhances electron transfer and active site exposure. • Fe 0.1 -Ni 9 S 8 /N-rGO achieves an overpotential of 255 mV at 50 mA cm −2 . • Fe doping shifts the d-band center down, weakening *O adsorption and lowering the RDS barrier. Developing effective, low-cost oxygen-evolution catalysts is essential for sustainable energy technologies. Here, we synthesized an N-doped reduced graphene oxide-supported, Fe-doped Ni 9 S 8 catalyst (Fe 0.1 -Ni 9 S 8 /N-rGO) by MOF-derived pyrolysis followed by sulfidation. To separate the effects of Fe-induced electronic modulation from N-rGO–assisted interfacial engineering, we prepared a series of control samples: Ni 9 S 8 , Ni 9 S 8 /N-rGO, Fe 0.1 -Ni 9 S 8 , and Fe 0.1 -Ni 9 S 8 /N-rGO. The optimized Fe 0.1 -Ni 9 S 8 /N-rGO exhibited efficient OER electrocatalysis, delivering 50 mA cm −2 at an overpotential of 255 mV with a Tafel slope of 54.58 mV dec −1 . Synergistic Fe doping and the Ni 9 S 8 /N-rGO heterojunction enhanced conductivity and increased active-site exposure, yielding higher activity. Electronic-structure analysis showed that Fe doping shifts the d-band center and tunes the interaction strength with key OER intermediates, which lowered the energy required for oxygen evolution. This work presents a logical strategy for designing high-performance, nonprecious-metal OER catalysts.