Self-cleaning dual cathode for enhanced durability of bipolar membrane-based direct seawater electrolysis

Direct seawater electrolysis offers a sustainable route to green hydrogen but remains limited by cathodic passivation caused by inorganic precipitate growth. Herein, we report a bipolar-membrane-based direct seawater electrolysis system integrating a dual-cathode configuration that enables self-cleaning of the cathode during long-term electrolysis. The two Pt/MoS 2 cathodes operate alternately every 48 h, allowing the inactive electrode to dissolve surface precipitates in the acidified seawater (pH ~2), while the other sustains the hydrogen evolution reaction (HER). This approach enables continuous hydrogen production without operational shutdowns, suppresses excessive scaling, and stabilizes cathodic potentials for over 400 h at 100 mA cm −2 . Compared with the single-cathode system, which exhibited severe passivation, high interfacial resistance, and significant Pt loss, the dual-cathode system preserved the structural integrity of MoS 2 nanosheets and Pt nanoparticles, demonstrating enhanced durability. Although HER activity partially degrades over long-term operation, the proposed dual-cathode self-cleaning strategy provides a practical solution to mitigate precipitation-induced cathodic passivation in direct seawater electrolysis and offers a viable pathway toward durable, scalable hydrogen production from natural seawater. • Bipolar membrane-based direct seawater electrolysis with a dual-cathode configuration enables self-cleaning of the cathode. • The active cathode produces hydrogen accompanied by inorganic precipitate growth, while precipitates formed on the resting cathode dissolve in acidified seawater. • Periodic cathode switching mitigates Mg(OH)₂ passivation and stabilizes interfacial resistance. • Dual-cathode operation suppresses Pt loss and structural damage in Pt/MoS₂ nanosheet catalysts, compared with single-cathode operation. • Continuous hydrogen production is achieved in natural seawater without shutdown or external chemical/mechanical descaling processes.