Interfacial Electronic Redistribution via Anionic Modulator for Superb and Highly Stable Water/Seawater Oxidation

Rational construction of efficient and stable transition-metal (TM)-based electrocatalysts for oxygen evolution reaction (OER) is extraordinarily favored and crucial to water/seawater splitting. Interface and heteroatom engineering are powerful strategies for improving the performance of the OER. Herein, we report a unique hydroxide/oxide heterostructure catalyst with P doping (Ni(OH)2/NiFe2O4–P) by an in situ growth strategy, following low-temperature phosphorylation for boosting water oxidation. The Ni(OH)2/NiFe2O4–P electrode, featuring an abundance of nanosheets, provides a greater number of functional active boundaries and enhances contact with the electrolyte for accelerated charge transfer. The incorporation of a P anionic modulator induces electron redistribution at heterogeneous interfaces, thereby tailoring the strong metal–anion interactions. Detailed electrochemical analysis further demonstrates that the Ni(OH)2/NiFe2O4–P heterostructure is an outstanding OER electrocatalyst, presenting low overpotentials of 224, 253, and 274 mV at 100 mA cm–2 in alkaline solution, alkaline simulated seawater, and alkaline natural seawater, respectively. The cell voltage of the assembled two-electrode electrolyzer (Pt/C ∥ Ni(OH)2/NiFe2O4–P) to deliver 10 mA cm–2 is only 1.62 V and can operate reliably for 150 h in an alkaline electrolyte.