Enabling stable seawater oxygen reduction via interfacial water modulation of partially-oxidized Te atomic clusters anchored on defective carbon

Catalyst passivation by metal hydroxide precipitation (e.g., Mg(OH) 2 ) severely hinders the oxygen reduction reaction (ORR) in seawater-based metal-air batteries. Herein, we propose an interfacial hydration layer engineering strategy and materialize it by constructing partially oxidized tellurium atomic clusters anchored on defective carbon nanofibers (PO-Te@CNF). This catalyst demonstrates superior ORR activity in natural seawater, with a high half-wave potential and large limiting current density surpassing Pt/C and most reported analogues, alongside remarkable long-term stability. The stability is attributed to a shift in Mg(OH) 2 nucleation from heterogeneous on the electrode to homogeneous in the electrolyte, which is driven by the reinforced hydration layer that raises the energy barrier for Mg 2 + penetration. Mechanistic studies reveal that the synergistic sites, comprising carbon defects and PO-Te clusters, concurrently optimize the local electronic structure to lower the ORR energy barrier and restructure the interfacial water network to inhibit cation intrusion. This work establishes a design principle for durable electrocatalysts in seawater-based energy technologies.