Rational Design of Iron Single Atom Anchored on Nitrogen Doped Carbon as a High-Performance Electrocatalyst for All-Solid-State Flexible Zinc-Air Batteries

Abstract Developing a cheap and high-efficiency oxygen reduction reaction (ORR) catalyst is vitally important for high-performance metal-air and full cells batteries. Non-noble iron-nitrogen-carbon materials (Fe-N-C) are reported with outstanding ORR property, however, most of them needs complex acid etching procedure during the fabrication process. Herein, we report a simple route to obtain a cost-effective Fe-N-C electrocatalyst via a facile two-step polymerization-pyrolysis process, and no acid etching is involved. Through a conjunction process of phthalocyanine iron (FePc) and polypyrrole (PPy) and a followed pyrolysis step, atomically evenly dispersed Fe-N-C species sites on nitrogen doped carbon can be easily obtained. Predictably, the obtained optimal catalyst delivers a half-wave potential of 0.83 V vs reversible hydrogen electrode (RHE) and better stability toward ORR test. Based on the optimal Fe single atomic catalyst as air cathode, an all-solid-state flexible Zn-air battery delivers a high open circuit voltage of 1.42 V, a high energy density of 833 Wh kg-1 and a high power density of 70 mW cm-2. Such superior electrochemical energy storage properties demonstrated by the Fe-N-C electrocatalyst shoves a bright window for reasonable construction of cost-effective non-noble Fe single atom electrocatalysts for next-generation flexible energy storage devices.