Interface-Engineered Integration of Nickel-Iron Phosphide with Carbon for Efficient and Stable Oxygen Evolution in Alkaline Media

Abstract

The development of robust, efficient, and cost-effective electrocatalysts is essential to address the sluggish kinetics of the oxygen evolution reaction (OER) in alkaline water electrolysis. This study prepared a novel nickel-iron phosphide supported on carbon (NiFe-P@C) composite via a two-step method: (i) continuous coprecipitation of NiFelayered double hydroxide (LDH) nanosheets on carbon supports in a Couette-Taylor flow reactor and (ii) phosphidation at elevated temperature. Taylor vortex flow enables uniform and rapid deposition of NiFe LDH onto the carbon surface, thereby promoting interfacial charge transfer and enhancing reaction kinetics. By tailoring the carbon content and optimizing phosphidation parameters, the resulting NiFe-P@C catalyst exhibited enhanced electrocatalytic performance and long-term operational stability in an alkaline electrolyte. Specifically, it delivered a low overpotential of 233 mV at a current density of 10 mA cm -2 and a Tafel slope of 44.8 mV dec -1 . Furthermore, in situ Raman spectroscopy combined with density functional theory calculations reveals that phosphorus incorporation effectively modulates the electronic structure and promotes the formation of catalytically active surface species during OER. This flow-assisted synthesis strategy provides a scalable, efficient route to high-performance bimetallic phosphide electrocatalysts for alkaline OER applications.