Interfacial Engineering of Ni ₂ P with Iron and Carbon toward Enhanced Robustness and Charge Transfer in the Oxygen Evolution Reaction

The oxygen evolution reaction (OER) plays a crucial role in water splitting, facilitating the generation of clean hydrogen fuel. Transition metal phosphides, particularly nickel phosphide (Ni2P), have attracted considerable attention as promising electrocatalysts for OER due to their high electrical conductivity and intrinsic catalytic activity. In this study, we propose a strategy to enhance the electrochemical performance of Ni2P through the incorporation of iron, manganese, or nickel species. To further improve electrical conductivity, the resulting nanoparticles were anchored onto a cellulose-derived carbon support. Among the synthesized materials, the composite consisting of nickel phosphide with 10 wt % iron (denoted as cel_Ni2P_Fe10) on a carbon platform exhibited the highest OER activity, achieving a low overpotential of 172.5 mV at a current density of 10 mA·cm–2 and a Tafel slope of 55.6 mV·dec–1, along with excellent long-term stability. Electrochemical impedance spectroscopy (EIS) revealed a significantly reduced charge transfer resistance compared with a benchmark RuO2 catalyst, indicating enhanced catalytic efficiency. Comprehensive physicochemical characterization confirmed that the incorporation of iron facilitates charge transfer processes and increases the availability of catalytically active sites. These findings offer valuable insights into the rational design of cost-effective and efficient electrocatalysts, contributing to the advancement of sustainable hydrogen production technologies.