Efficient and Selective Oxygen Evolution Reaction in Seawater Electrolysis with Electrochemically Synthesized Amorphous-like NiFeS

For the heterogeneous alloy catalysts of water electrolysis, it has been reported that conductivity can be improved through structural modifications by introducing other elements like chalcogens. Transition metal sulfides can induce numerous lattice defects due to their unique interface formation, thereby promoting abundant active sites and facilitating electron/ion movement. In this study, we report the enhanced electrochemical activity of NiFeS formed on nickel foam (NiFeS@NF) for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) during the water electrolysis, especially, the seawater electrolysis. NiFeS@NF synthesized through a one-step electrochemical deposition had an amorphous-like highly porous structure with the aggregates of spherical nanoparticles attached to nickel foam. Compared to NiFe@NF, NiFeS@NF catalysts demonstrated a reduced overpotential by ~32 mV and ~96 mV for OER and HER, respectively, at 100 mA cm⁻² and secured electrochemical stability over 24 h. Moreover, bifunctional seawater electrolysis using NiFeS@NF as both electrodes demonstrated the reduced overpotential by ~80 mV with durability over time. This facile synthesis method for anion doping and  the enhanced and selective electrolysis of seawater without producing Cl₂ gas holds promise for the creation of high-performance electrocatalysts applicable in a wide range of hydrogen energy-related fields.

Graphical Abstract