Interfacial configuration of heterogeneous NiFe–sulfide as a highly electrocatalytic selective oxygen evolution reaction electrode toward seawater electrolysis

Abstract

Seawater electrolysis for scalable hydrogen generation has attracted much attention due to the abundance of seawater in nature. However, it is severely impeded by the chlorine ions in seawater, which can cause corrosion and an undesirable competing reaction at the anode. So it is highly desirable to exploit a highly active, chlorine corrosion resistant and selective OER electrode for seawater splitting. Here, a heterogeneous NiFe–sulfide electrode is proposed to achieve an efficient OER process in alkaline seawater. Considering the 2D lamellar architecture with a rough surface and a considerable amount of micro voids, the dual electronic configuration of sulfur and iron, the strong synergistic effect between Ni and Fe at the atomic level and the interfacial engineering between the NiS/Ni₃S₂ phase and FeS phase at the nanoscale level, the Ni₆Fe₂S-0.05 M electrode exhibits predominant catalytic activity with an overpotential of 353 mV to reach 200 mA cm⁻², superior long-term stability with 50 h accelerated stability test and higher selectivity toward the OER.