Engineering built-in electric field in NiMoO4/FeOOH heterostructures for efficient oxygen evolution reaction

A polarized crystalline/amorphous interface is constructed for OER catalysis. • Built-in electric fields regulate dynamic electrochemical reconstruction. • Efficient hydrogen production is achieved under harsh alkaline conditions. Efficient and durable oxygen evolution reaction electrocatalysts are essential for industrial-scale hydrogen production, yet regulating electrochemical reconstruction while maintaining structural stability remains challenging. Herein, a crystalline-weakly crystalline NiMoO 4 @FeOOH heterostructure is constructed to enable built-in electric field (BEF)-driven reconstruction regulation. The Fermi-level mismatch at the heterointerface induces charge redistribution and generates a polarized BEF, which directs the reconstruction pathway toward highly active NiFeOOH species while suppressing excessive structural degradation. The optimized catalyst achieves a low overpotential of 255 mV at 100 mA cm −2 , a Tafel slope of 52.1 mV dec −1 , and stable operation for 100 h in 30 wt% KOH at 80 °C, with an energy consumption of 4.84 kWh Nm −3 H 2 . Operando Raman, in situ electrochemical impedance spectroscopy, and XPS analyses reveal that the BEF accelerates Ni oxidation, promotes OH − adsorption, and facilitates interfacial charge transfer during reconstruction. Density functional theory calculations further confirm optimized oxygen intermediate adsorption and reduced reaction barriers. This work establishes a BEF-driven electrochemical reconstruction strategy for coupling interfacial electronic regulation with dynamic catalyst evolution toward high-performance OER electrocatalysts. Download: Download high-res image (154KB) Download: Download full-size image