Graphene layers-wrapped FeNiP nanoparticles embedded in nitrogen-doped carbon nanofiber as an active and durable electrocatalyst for oxygen evolution reaction

The development of active and robust electrocatalysts for water splitting, especially the non-precious-metal electrocatalysts with well-defined nanostructures, has attracted much attention. Herein, we report a nitrogen-doped carbon nanofiber embedded with ultrafine graphene layers-wrapped FeNiP nanoparticle (denoted as FeNiP@N-CFs) by direct pyrolysis reduction of electrospun Fe³⁺/Ni²⁺/polyacrylonitrile precursor fibers followed by in situ phosphorization. Benefiting from the high electrochemical activity of in situ formed FeNiP/FeNiOOH core-shell nanoparticles during test, strong coupling with few layers graphene shell, and synergistically enhanced electronic conductivity of N-doped carbon nanofiber matrix, the as obtained FeNiP@N-CFs exhibits outstanding electrocatalytic activity, in terms of a low overpotential (300 mV at 10 mA cm⁻²), small Tafel slope of 47 mV dec⁻¹ and remarkable long-term stability in 1.0 M KOH for oxygen evolution reaction (OER). This work provides a general approach for fabrication of double-metal phosphide-graphitized carbon nanofiber hybrid electrodes with enhanced conductivity and catalytic activity for electrochemical water oxidation.