Interface engineering of crystalline Fe-Ni₃S₂/amorphous FeOOH heterostructures for enhanced hybrid supercapacitors and oxygen evolution reaction

The development of high-performance multifunctional electrodes for both supercapacitors and the oxygen evolution reaction (OER) is critical for advancing energy storage and conversion systems. Herein, a self-supported Fe-Ni₃S₂/FeOOH heterostructure on nickel foam (Fe-Ni₃S₂/FeOOH@NF) is fabricated via a combined hydrothermal-electrodeposition method. The abundant heterogeneous interfaces between crystalline Fe–Ni₃S₂ and amorphous FeOOH induce strong electronic interactions, which significantly enhance charge transfer and reaction kinetics, especially for supercapacitors. As a supercapacitor electrode, the Fe-Ni₃S₂/FeOOH@NF electrode delivers a high specific capacitance of 838 F g−1 at 1 A g−1. The assembled hybrid supercapacitor device achieves a specific capacitance of 63 F g−1 and exhibits outstanding cycling stability, retaining 87.3% of its initial capacity after 10,000 cycles. Furthermore, the electrode demonstrates notable electrocatalytic performance for the OER, requiring a low overpotential of 262 mV to reach 50 mA cm−2. These results underscore the great potential of the Fe-Ni₃S₂/FeOOH@NF as a high-performance, multifunctional material for advanced energy storage applications.