Microenvironment‐Engineered Multilayered Electrode Design for Sustainable Seawater Oxidation

The reliance on high-purity water for hydrogen production increases the strain on freshwater resources. Direct seawater electrolysis is a promising alternative but is impeded by complex challenges such as chloride-induced corrosion and electrode surface fouling. Herein, a microenvironment-engineered, multilayered electrode design for sustainable seawater electrolysis is presented, utilizing the strategic integration of carbonate (CO₃²⁻) Lewis base sites anchored on a Cobalt layered double hydroxides (Co LDH) embedded within a NiBO_x nanostructure supported by a Ni(OH)₂/NF microarray. Incorporating boron into the Ni-OOH matrix forms a protective metaborate film, preventing metal dissolution and non-conductive oxide formation, thereby enhancing current collector corrosion resistance in saline seawater conditions. The CO₃²⁻ Lewis base covalently functionalized on Co-active sites, establishes a dynamic interaction that continuously splits water molecules while sequestering H⁺ ions, generating a localized acidic microenvironment. This acidification enhances OER kinetics and protects against chloride attack and precipitate formation, addressing key stability and efficiency barriers in direct seawater electrolysis. The advanced anode design achieves an industrially viable current density of 1.0 A cm⁻² at 1.65 V under standard conditions, marking a significant step toward scalable, desalination-free hydrogen production directly from seawater.