Electron‐Isolating Band Solidified Fe─O Bond in Ni/NiFe Layered Double Hydroxide Composite for Stable Ampere‐Level Simulated Seawater Oxidation

Abstract

ABSTRACT The dissolution of iron ions triggers irreversible structural collapse and resultant catastrophic deactivation in NiFe‐layered double hydroxides (NiFe LDHs), representing a formidable challenge to their implementation in sustainable hydrogen production. Herein, by adjusting the Ni nanoparticle content in Ni/NiFe LDH composites synthesized via reduction–coprecipitation method, Fe t 2g orbital occupancy is regulated to protect the Fe─O bond from cleavage. Specifically, with considerable electron transfer from Ni to Fe t 2g orbital, the low‐energy antibonding of Fe t 2g * band separates from the (Fe─O) bonding band, lying near and crossing the Fermi level, as evidenced by x‐ray absorption spectra (XAS) and the calculated density of states. This band serves as an electron‐isolating band to avoid electron removal from the (Fe─O) bonding band, which significantly solidifies the Fe─O bond confirmed by operando XAS. Additionally, the modulation lowers the adsorption energy of Cl − , suppressing the chloride‐induced electrocatalyst corrosion in seawater electrolysis. Consequently, the optimal sample operates stably at 1 A cm −2 for over 10 000 h in the three‐electrode system and beyond 450 h in an anion‐exchange membrane water electrolyzer under simulated seawater oxidation, ranking among the state‐of‐the‐art powder‐type NiFe LDH‐based catalysts. This work highlights the manipulation of antibonding orbital state for fundamentally enhancing electrocatalyst stability.