FeCo-Ni₅P₄ Nanosheet Arrays on Carbon Fibers as Electrocatalysts for Water Splitting

Rational design of efficient catalysts with high activity and prolonged stability to overcome the sluggish kinetics of electrocatalytic water splitting is imperative but challenging. The optimization of electrocatalysts’ components and geometric structure is deemed an effective strategy. Herein, Fe, Co co-doped Ni5P4 hierarchical cube-on-sheet nanoarrays grown on coal-based carbon nanofibers (FeCo-Ni5P4@C–CNFs) was synthesized by electrospinning, hydrothermal methods, coprecipitation, and phosphorization. Benefiting from metal doping with a strong interaction for electron transfer, the cube-on-sheet architecture with excellent superhydrophilic and aerophobic properties for mass transportation, and self-supported C–CNFs as a conductive substrate with remarkable structural durability, the obtained FeCo-Ni5P4@C–CNFs displays superior bifunctional electrocatalytic properties. In 1.0 M KOH electrolyte, the overpotentials of hydrogen evolution and oxygen evolution reactions are only 46 and 221 mV at a current density of 10 mA cm–2, respectively. In addition, the assembled FeCo-Ni5P4@C–CNFs electrolyzer requires a low cell voltage of 1.50 V at 10 mA cm–2. This study offers a method for the rational design of highly active electrocatalysts and also enriches the means of component and structure modulation of transition metal phosphides.