Nitrogen-doped carbon decorated-Ni3Fe@Fe3O4 electrocatalyst with enhanced oxygen evolution reaction performance

Abstract

• Facile approach to transform NiFe 2 O 4 into N -doped carbon decorated-Ni 3 Fe@Fe 3 O 4 . • Polydopamine effect on the overall structure and OER performance of NiFe 2 O 4 . • Ni 3 Fe and Fe 3 O 4 active sites provide favorable reaction kinetic and stability. High performance, durable and inexpensive electrocatalyst for oxygen evolution reaction (OER) is of great importance for tenable hydrogen production via water electrolysis. Although spinel oxides (AB 2 O 4 , A, B = metal) represent a class of promising candidates for OER, their intrinsically poor electrical conductivity impacts their electrochemical performance. Herein, we employed a facile approach to transform an intrinsically low active NiFe 2 O 4 into nitrogen-doped carbon decorated Ni 3 Fe@Fe 3 O 4 catalyst with improved activity and stability for alkaline OER. Initially, a pristine NiFe 2 O 4 octahedron-like structure was synthesized by a hydrothermal route. Then, series electrocatalysts were prepared by incorporating the pristine NiFe 2 O 4 with different dopamine concentrations via in-situ polymerizations of dopamine followed by carbonization. The morphology, crystalline structure, and chemical composition of the catalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma (ICP). The OER electrocatalysis performance was measured in a standard three-electrode system. The effect of the carbonized dopamine on the electrocatalytic activity and structure of the NiFe 2 O 4 precursor was systematically investigated. Among several NiFe electrocatalysts, the one with 10 wt% of dopamine (NiFe/NC 10% ) exhibited a relatively higher catalytic activity for OER tested in 1.0 M KOH; unveiled low overpotential (350 mV at 10 mAcm −2 current density), a low Tafel slope (56 mVdec −1 ), low charge transfer resistance, relatively higher electrochemically active surface area. Most prominently, it remained stable for at least 12 h. This work provides a new perspective for functionalizing metal oxides and affords a facile synthesis approach, low-cost, high-performance, and robust electrocatalyst for alkaline OER electrodes.