FeNi₂S₄/NF as a Highly Efficient Electrocatalyst for Seawater Splitting

For the generation of electrolytic hydrogen, the development of high-performance oxygen evolution reaction (OER) electrocatalysts is crucial. This work reports a high-performance OER electrocatalyst prepared by acid etching and ion exchange strategies. Because of its high adhesion, superhydrophilicity, and rough surface, the produced FeNi2S4/nickel foam (NF) catalyst showed exceptional OER performance in both alkaline electrolyte and alkaline seawater electrolyte. Particularly, the negatively charged sulfate layer formed by FeNi2S4/NF after the OER reaction can effectively prevent Cl-anion poisoning of the catalyst. Low overpotentials of 234 and 295 mV in an alkaline saltwater electrolyte are needed for the FeNi2S4/NF catalyst to produce current densities of 10 and 100 mA cm–2, respectively. Using this OER catalyst in combination with an efficient hydrogen evolution reaction catalyst, we were able to achieve overall alkaline seawater electrolysis at room temperature with very good durability with current densities of 10 and 100 mA cm–2 at low voltages of 1.54 and 1.70 V, respectively. The electrolysis of seawater has a promising application for this effort.