N,S-Codoped Carbon Nanostructures Encapsulated with FeNi Nanoparticles as a Bifunctional Electrocatalyst for Rechargeable Zn–Air Batteries

The exploration of highly efficient, low-cost, and durable oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) bifunctional electrocatalysts is extremely desirable but challenging for the practical application of Zn–air batteries. Herein, we report the fabrication of a FeNi alloy nanoparticle (NP)-decorated N,S dual-doped carbon nanocomposite (denoted FeNi/NS-C) as a bifunctional electrocatalyst for Zn–air batteries. The FeNi/NS-C electrocatalyst is produced through the complexation of a N-rich imidazolyl-phenanthroline derivative with metal salts, followed by pyrolysis in the presence of trithiocyanuric acid (TTCA). The FeNi/NS-C electrocatalyst shows comparable ORR activity to that of Pt/C (E1/2 = 0.83 V) and superior OER activity to that of IrO2 (Ej=10 = 1.585 V). The liquid- and solid-state Zn–air batteries assembled with the FeNi/NS-C exhibit high power density and specific capacity. In particular, the FeNi/NS-C-based Zn–air batteries display remarkable durability over 1000 h at 5 mA cm–2 and 70 h at 2 mA cm–2 in liquid and solid electrolytes, respectively. The high performance of the FeNi/NS-C may be related to the synergistic effect of the bimetallic alloy NPs and the N,S dual-doped carbon matrix with a high surface area, porous structure, and unique hybridized morphology.