Built-in electric field triggered interfacial electron accumulation and structural reconstruction for boosting ampere-level-current seawater oxidation

Abstract

During the water splitting process for hydrogen production with metal hydroxide electrocatalysts, a self-reconstructing reaction occurring at low potential is the key to efficient operations. In this work, a Ni-Fe(OH)₃ electrocatalyst is designed, in which the built-in electric field formed at the heterojunction results in electron accumulation on Ni and facilitates the reconstruction of Fe(OH)₃ into active FeOOH under a lower applied potential while maintaining structural stable. Triggered by the interfacial electron accumulation and structural reconstruction, the prepared Ni-Fe(OH)₃ anchored on an iron-nickel-foam substrate shows an overpotential of just 453 mV that can drive an ampere level current of 1.0 A cm⁻² in 1.0 M KOH mixed seawater, with remarkable stability for over 360 h. Density functional theory calculations suggest that the in-situ reconstructed Ni-FeOOH enhances the adsorption behavior of intermediates and significantly reduces the energy barrier of the oxygen revolution reaction. These results underscore the great promise of engineering built-in electric field in transition metal hydroxide catalysts for efficient hydrogen production via seawater oxidation。