Strain-engineered FeNi@SDC heterointerfaces for durable high-temperature seawater electrolysis

Hydrogen production from seawater using solid oxide electrolysis cells (SOECs) offers a promising pathway towards a sustainable energy future. However, severe Ni catalyst coarsening and chloride-induced surface poisoning under high-temperature steam conditions still limit long-term operation. Herein, we develop a reduction-driven strategy to construct strain-engineered FeNi@SDC heterointerfaces by infiltrating an FeSDC (Sm 0.2 Ce 0.7 Fe 0.1 O 2-δ ) precursor into a commercial nickel-yttria-stabilized zirconia (Ni-YSZ) fuel electrode. Partial Fe diffusion into the Ni lattice during reduction drives the in-situ formation of FeNi alloy nanoparticles, simultaneously generating lattice strain and a robust metal-oxide heterointerface. Theoretical calculations show that these coupled structural features regulate the electronic structure of Ni, thereby promoting water activation, optimizing hydrogen adsorption and suppressing chloride adsorption. As a result, the modified electrolysis cell achieves an electrolysis current of 52.7 A at 1.5 V, while maintaining stable operation for 645 h with an ultralow degradation rate of 8.4 × 10 −4 % h −1 . This work establishes a general strategy that integrates alloy-induced lattice strain with heterointerface engineering for the development of durable fuel electrodes for high-temperature seawater electrolysis .