NiFe Layered Double-Hydroxide and Cobalt-Carbon Composite as a High-Performance Eletrocatalyst for Bifunctional Oxygen Electrode

A novel non-precious composite catalyst containing NiFe layered double hydroxide (NiFe LDH) and cobalt-carbon composite (CoC) was prepared for bifunctional oxygen electrode. The structure and morphology of the composite was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Electrochemical performance was tested by electrochemical impedance spectroscope (EIS) and linear sweep voltammetry (LSV) in 6 M KOH electrolyte. The oxygen electrode with NiFe LDH-CoC/AB shown excellent electrocatalytic activity for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) with the current density of 289, 41 mA cm(-2) recorded at 0.70, 0.20 V vs. Hg/HgO, respectively, significantly higher than Pt/C electrode (70 mA cm(-2), 30 mA cm(-2)). Tested at the current density of 40 mA cm(-2) with 2 h per cycle in a zinc air battery, the bifunctional oxygen electrode exhibited unexpected cycling stability in 200 cycle periods with stable charge/discharge voltages of 2.05 V and 1.05 V. (C) 2015 The Electrochemical Society.