From Lab to Ocean: Multiscale Design of Electrocatalysts for Practical Seawater Splitting Applications

Under the carbon peak and neutrality targets, green hydrogen is a cornerstone for zero-carbon energy systems. Constrained by freshwater scarcity, conventional water electrolysis faces bottlenecks, making direct seawater electrolysis (DSE) a promising route. However, complex seawater components induce chloride corrosion, metal precipitation, and membrane fouling, severely hindering practical applications. This review transcends the sole focus on electrocatalysts, emphasizing multi-level synergy across materials, interfaces, devices, and marine environments toward realistic ocean conditions. We systematically elucidate reaction competition, ion interactions, and interfacial microenvironment evolution, providing a cross-scale summary from catalysts to membranes and electrolyzers, with a four-dimensional evaluation framework. Recent kW-to-MW demonstrations validate technical feasibility. Future integration of DSE with offshore renewables and marine resource utilization will overcome bottlenecks and promote carbon neutrality.