Synergistic hydroxide enrichment and chloride repulsion for Ampere-level stable seawater oxidation

Abstract Benefiting from the abundant renewable energy supply in coastal regions, electrochemical seawater splitting for green hydrogen production shows great potential. However, the chloride (Cl−)-rich nature of seawater creates a highly corrosive environment, posing a significant obstacle to the anodic stability. Herein, a rationally designed catalyst with multiple protections, containing strong Cl− repulsion, OH− enrichment, and local pH regulation, is applied for robust electrochemical alkaline seawater oxidation (eASO). In the eASO process, Zr will form ZrOx species acting as Lewis sites during this process, which exhibit a strong affinity toward OH−. This effectively mitigates the negative impact of the electrostatic protective layer on OH− transport, enhances the surface OH− coverage, and further promotes phase transformation. In addition, low-valent Pδ− will be oxidized to PO43−, which subsequently adsorbs onto the surface of active MOOH (M = Co) sites, forming a dual-functional protective layer that provides proton buffering and Cl− repulsion. Overall, such a designed anode achieves a 1500 h stable eASO at 1 A·cm−2 without any activity degradation, providing a new feasible design strategy for the green seawater-to-H2 system.