The rapid self-reconstruction of Fe-modified Ni hydroxysulfide for efficient and stable large-current-density water/seawater oxidation

The reasonable design of electrocatalysts with rapid self-reconstruction for an efficient oxygen evolution reaction (OER) at commercially required current densities is highly desirable but very challenging. Herein, ultrathin Fe-modified Ni hydroxysulfide (Fe-NiSOH) nanosheet arrays were grown in situ on Ni foam via a simple two-step oxidation strategy for efficient and stable large-current-density water/seawater oxidation. Systematic insights, including experimental and theoretical analysis, reveal that in situ S leaching from the electrode boosts its self-reconstruction and results in the more-ready generation of highly active Ni4+ species, which benefits from a reduced formation energy. Owing to its excellent physical and chemical properties, the Fe-NiSOH catalyst requires only low overpotentials of 207, 240, and 268 mV in alkaline water to deliver current densities of 10, 100, and 500 mA cm(-2), respectively, and it can work stably for 1100 hours at the commercially required current density of 500 mA cm(-2). Furthermore, it also exhibits excellent seawater oxidation activity and superior resistance to Cr corrosion, since it can run stably at 500 mA cm(-2) for over 900 hours. This work offers an efficient strategy to build rapidly self-reconstructing electrocatalysts to promote the formation of highly oxidized metal species for efficient and stable water/seawater oxidation.