Constructing a dual-protection heterointerface for durable anion exchange membrane seawater electrolysis at ampere-level current density

Chloride ions (Cl⁻) pose a corrosive challenge to the long-term durability of metal catalysts during seawater electrolysis for sustainable hydrogen production. The construction of heterointerfaces has been demonstrated to enhance the corrosion resistance of highly active transition metals by preventing direct contact with Cl⁻ in seawater. However, reliance on a single protection mechanism has hindered further advances in heterojunction catalysts. In particular, the charge-transfer regulation induced by the spatial electric field at heterointerfaces has often been overlooked. Herein, we investigate the Cl⁻ corrosion behavior at the graphene/NiMo interface, which serves as a hydrogen evolution catalyst for durable seawater electrolysis. The spatial electric field formed at the heterointerface promotes the electron density on the graphene surface, thereby suppressing Cl⁻ accumulation through electrostatic repulsion. Furthermore, doping the graphene layer with a strong electron-accepting element can significantly improve electron transfer and enhance Cl⁻ resistance. In addition, the formation of C–Cl bonds on the graphene surface inhibits the diffusion of Cl⁻ toward the metal through a steric effect. N-doped graphene-encapsulated NiMo (NG/NiMo) achieves a current density of 1.0 A cm⁻² at 1.86 V in an anion exchange membrane (AEM) electrolyzer using seawater as the feedstock, maintaining durability for over 300 h. This work provides new insights into constructing a dual-protection heterointerface by combining electrostatic repulsion and the steric effect to achieve long-term protection for metal catalysts in seawater.