“Armor sacrifice layer” prolongs boron-base electrode lifespans at industrial-level current densities toward overall seawater splitting

Abstract Seawater electrolysis for hydrogen production offers a promising source of virtually unlimited clean energy without relying on freshwater resources. However, the presence of halide ions (Cl⁻, Br⁻) in seawater poses a significant challenge to achieving efficient and sustained electrolysis. In this work, we propose a strategy to enhance the long-term catalytic stability of boron-based electrodes in seawater through the use of a protective "sacrificial armor layer." Chromium (Cr) is introduced as this sacrificial layer; during anodic oxidation, it gradually leaches out, generating chromate ions (CrO₄ 2 ⁻) in situ. These ions adsorb onto the anode surface and effectively repel chloride ions via electrostatic repulsion, thereby shielding the electrode from corrosion. Attractively, the Cr-NiB@HP flexible electrode operates stably for more than 1400 and 720 h at current densities of 100 and 500 mA cm −2 , respectively, demonstrating excellent stability. The designed "filterable" electrode can be directly used for one-step in-situ filtration catalysis in special environment (seawater, sewage, or lake water) systems. This work reveals the construction of a corrosion-resistant filterable electrode, which holds promise for application in large-scale industrial seawater electrolysis. Graphical Abstract Filterable Cr-NiB@HP electrode is applied in multiple scenarios and achieved excellent long-term stability in overall seawater splitting. Cr species leached from the surface of the electrode during electrolysis effectively protect the active species of the electrode from chloride ions in seawater. The filtered electrodes can be used in AEM electrolyzers, and the assembled homemade hydrogen production unit can achieve a hydrogen production efficiency of 320 mL min -1 , realizing initial industrial applications.