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

Abstract

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 /NiFe 2 O 4 −P) by an in situ growth strategy, following low-temperature phosphorylation for boosting water oxidation. The Ni(OH) 2 /NiFe 2 O 4 −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 /NiFe 2 O 4 −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 /NiFe 2 O 4 −P) to deliver 10 mA cm −2 is only 1.62 V and can operate reliably for 150 h in an alkaline electrolyte.