Anion Exchange Membrane Seawater Electrolysis at 1.0 A cm−2 With an Anode Catalyst Stable for 9000 H

Abstract

Hydrogen production through seawater electrolysis is promising but challenging due to severe anode corrosion by chlorine (Cl−) ions. Herein, a corrosion-resistant NiFe layered double hydroxide electrode (CAPist-S1) is reported as a high-performance electrocatalyst for seawater oxidation, achieving an industrial-level current density of 1.0 A cm−2 at overpotentials of 200 and 220 mV in alkaline simulated (1 M KOH + 0.5 M NaCl) and natural (1 M KOH + seawater) seawater, respectively, along with extraordinary long-term stability over 9000 h under 1.0 A cm−2 in alkaline natural seawater. A dense NiFe LDH interlayer generated between the NiFe LDH nanosheets and metal substrate is found to efficiently retard the penetration of Cl− ions to the substrate surface, improving the resistance to Cl− ions corrosion. Furthermore, this dense interlayer is an essential prerequisite for establishing a dynamic equilibrium between Fe leaching and redeposition over the in situ formed FeOOH, and this dynamic equilibrium can in turn stabilize the dense interlayer, maintaining the activity of CAPist-S1 during prolonged electrolysis. Using CAPist-S1 in an anion exchange membrane (AEM) seawater electrolyzer, the obtained electrolyzer stably functions over 700 h at 1.0 A cm−2 under room temperature, indicating promising prospects for industrial seawater electrolysis application.