Introducing Sulfur to Nickel-Iron Selenide for High-Efficiency Alkaline Seawater Electrolysis

Seawater electrolysis is an effective way to obtain hydrogen (H2) in a sustainable manner. However, the lack of electrocatalysts with high activity, stability, and selectivity for oxygen evolution reaction (OER) severely hinders the development of seawater electrolysis technology. Herein, sulfur-doped nickel-iron selenide nanosheets (S-NiFeSe2) were prepared by an ion-exchange strategy and served as highly active OER electrocatalyst for alkaline seawater electrolysis. The overpotential is 367 mV, and it can run stably for over 50 h at 100 mA cm−2. Excitingly, the S-NiFeSe2∥Pt/C pair exhibits cell voltage of 1.54 V at 10 mA cm−2 under alkaline seawater conditions, which can run smoothly for 100 h without decay, and the efficiency of electricity-to-hydrogen (ETH) energy conversion reaches more than 80