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

Abstract

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 Cl⁻ 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.