Surface and Interfacial Engineering of Electrocatalysts for Seawater Electrolysis

Conspectus By tapping Earth’s most abundant water resource, seawater electrolysis offers a promising route to hydrogen production while reducing reliance on freshwater. However, in natural seawater and at industrial current densities ( j ), complex ion–catalyst interactions at the interface can accelerate activity decay and undermine long-term durability. On the anode, halide attack dominated by Cl – can shift selectivity from the oxygen evolution reaction toward the chlorine evolution reaction and trigger the metal-chloride/hydroxide corrosion pathway, causing loss of active sites and poor oxygen selectivity. On the cathode, the local pH increase induced by the hydrogen evolution reaction can drive Mg 2+ /Ca 2+ precipitation, forming fouling layers that block active sites and hinder continuous operation. Additionally, inadequate control of gas release and the solid–gas interface at industrial j can accelerate bubble-induced mechanical damage to the catalyst layer. In this Account, we summarize our group’s progress in engineering catalyst surfaces and interfaces toward efficient and durable seawater electrolysis. We begin by outlining anode-focused strategies that improve seawater oxidation activity and halide tolerance. First, anion-species regulation is applied to (1) construct anion-rich surfaces that repel Cl –, (2) engineer a Lewis-acid-enabled OH – -enriched microenvironment that favors *OH over Cl –, and (3) build a high-density negatively charged network that efficiently excludes Cl – at industrial j . Next, surface coordination regulation is introduced in which strongly chemisorbed molecular regulator tunes the electronic structure of metal centers and reinforces Cl – repulsion. Subsequently, we design a multidefense architecture that integrates an anion-rich surface and oxygen-intermediate-rich layer within a tip-connected bubble management framework, enabling simultaneous mitigation of chlorine chemistry and mechanical stress at industrial j . On the cathode side, we develop a microscopic bubble/precipitate traffic system (MBPTS) and self-cleaning electrode that control gas and ion transport, continuously remove Mg 2+ /Ca 2+ deposits, and enable concurrent H 2 production and magnesium recovery. Finally, we outline the remaining limitations and emerging opportunities in seawater electrolysis to inspire next-generation designs for saline electrochemical energy systems and beyond.