Navigating Interfacial Complexities in Direct Seawater Electrolysis: Towards Scalable and Sustainable Green Hydrogen

ABSTRACT Direct seawater electrolysis (DSE) presents a transformative pathway for decentralized, scalable green hydrogen production, circumventing the high energy demands and environmental burdens associated with conventional desalination‐coupled systems. However, its industrial translation is fundamentally bottlenecked by interfacial instabilities, primarily driven by the complex multi‐ion and microbial matrix of natural seawater. Herein, we provide a comprehensive review of the failure mechanisms in DSE, critically examining the interplay of anodic chlorine competition and corrosion, cathodic mineral scaling induced by local alkalization, and microbially influenced corrosion. To bridge the critical gap between laboratory prototypes and industrial demands, we propose a cross‐scale design framework. At the microscale and mesoscale, we delineate cutting‐edge interfacial modulation strategies, such as adsorption competition at active sites, dynamic ion shielding, and anti‐adhesion engineering, aimed at reconstructing the local electrochemical microenvironment. At the macro‐scale, we systematically evaluate advanced system integration paradigms, such as bipolar membrane configurations, asymmetric feeds, and forward osmosis coupled electrolyzers, which decouple complex mass transport from catalytic sites. Finally, integrating recent techno‐economic analyses (TEA) and offshore pilot projects, we outline the roadmap toward establishing standardized real seawater testing protocols and mitigating scaling up risks.