Communication—Fe/FeNi 3 Embedded in Nitrogen-Doped Carbon Nanotubes as Bifunctional Oxygen Electrocatalysts

Abstract

Both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucial for metal-air batteries. Achieving a single phase that offers both functionalities is of practical relevance. Here, we report a facile method to couple Fe-Nx moieties and FeNi3 nanoparticles, and embed these in nitrogen-doped carbon nanotubes (Fe/FeNi3@NC). The Fe/FeNi3@NC catalyst demonstrates excellent bifunctional performance in 0.10 molar potassium hydroxide. We observe a half-wave potential of 0.83 V for ORR, and a potential of 1.58 V at a current density of 10 mA cm−2 for OER. The oxygen electrode fabricated using Fe/FeNi3@NC exhibits a peak power density of 143 mW cm−2 for rechargeable Zn-air battery. Over a ∼9 h duration test, the material is also shown to be as stable as the commercial Pt/C + IrO2 in operating conditions.