NiFe-based arrays with manganese dioxide enhance chloride blocking for durable alkaline seawater oxidation

Seawater splitting is increasingly recognized as a promising technique for hydrogen production, while the lack of good electrocatalysts and detrimental chlorine chemistry may hinder further development of this technology. Here, the interfacial engineering of manganese dioxide nanoparticles decorated on NiFe layered double hydroxide supported on nickel foam (MnO₂@NiFe LDH/NF) is reported, which works as a robust catalyst for alkaline seawater oxidation. Density functional theory calculations and experiment findings reveal that MnO₂@NiFe LDH/NF can selectively enrich OH^- and repel Cl^- in oxygen evolution reaction (OER). MnO₂@NiFe LDH/NF attains a current density of 1000 mA cm^-2 in alkaline seawater with an ultralow overpotential of only 313 mV. Furthermore, it can maintain stability at 1500 mA cm^-2 over 600 h. Further phosphidation of MnO₂@NiFe LDH/NF can create MnO_x@NiFeP/NF used in efficient hydrogen evolution reaction. Moreover, an anion exchange membrane electrolyzer with MnO₂@NiFe LDH/NF as the anode and MnO_x@NiFeP/NF as the cathode was also capable of seawater splitting at 500 mA cm^-2 for 100 h. This work offers light to develop effective and long-lasting electrocatalysts for seawater splitting.