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.