Microwave Field Enhancement at Metal-Electrolyte Interfaces Enables Rapid Growth of Fe-Ni<sub>3</sub>S<sub>2</sub> on Nickel Foam for Alkaline Oxygen Evolution.

Abstract

High-performance oxygen evolution reaction (OER) catalysts must combine low overpotential, fast electron/ion transport, low-cost scale-up production, and long-term durability under alkaline operation. Although Fe-doped Ni₃S₂ is considered a catalyst satisfying the conditions, rapid uniform growth of Fe-Ni₃S₂ on metallic Ni supports remains challenging. Herein, we circumvent this long-standing obstacle by harnessing a localized microwave field enhancement effect at the electrode-electrolyte interface. This strategy enables rapid (15 min) and low-power (75 W) growth of a highly crystalline Fe-Ni₃S₂ catalyst directly on the Ni foam substrate. The as-synthesized catalyst shows exceptional OER performance, exhibiting a low overpotential of 270 mV at 100 mA cm^-2 and outstanding durability for over 100 h. Moreover, the successful operation of an anion exchange membrane water electrolysis device demonstrates its practical feasibility. This study not only unveils a superior OER electrocatalyst but also establishes the principle of microwave field enhancement as a new and powerful paradigm for the energy-efficient synthesis of functional materials directly on metallic platforms.