Stepping Electric Field Enables Durable Water Electrolysis

The industrial application of NiFe-based electrocatalysts faces a critical challenge from Fe 3+ dissolution during alkaline water electrolysis. A breakthrough Fe/FeNi 3 @NiFeOOH heterostructure is reported that achieves remarkable industrial-grade performance, demonstrating both an ultralow overpotential (200 mV@100 mA cm −2 ) and unprecedented stability (>1800 h@70 °C, 1.7 V vs reversible hydrogen electrode, RHE). The exceptional stability stems from two synergistic effects: 1) a stepping interface electric field that stabilizes low-valence Fe species through electrostatic confinement, and 2) dynamic interfacial equilibrium maintained via uphill diffusion of trace Fe ions from electrolyte (ppm-level). This work provides a fundamental design strategy of highly stable electrocatalysts, paving the way for practical industrial-scale water electrolysis.