Potassium-Ion Activating Formation of Fe-N-C Moiety as Efficient Oxygen Electrocatalyst for Zn-Air Batteries

Developing a new synthesis methodology to obtain an economical and stable single atom oxygen reduction reaction (ORR) catalyst is highly desirable. Herein, we develop a general ionic salt assisted template method to obtain M-N-C (M=Fe and Co) catalyst with improved ORR activity. The creation of M-N-C single atom catalyst is highly dependent on the nature of ionic salt templates. Compared with NaCl, KCl can not only act as template, but also create more defect sites for single iron atom to anchor through metallic K-intercalation activation at elevated temperatures, which results in the generation of more single atomic M-N-C active sites. Furthermore, the ionic salt template-assisted method leads to the formation of interconnected porous structure with sufficient micropores and a high surface area of 514 m(2) g(-1). As an ORR and Zn-air battery catalyst, Fe-N-C-KCl shows a half-wave potential of 0.877 V and a maximum power density of 185 mW cm(-2), respectively, outperforming those of state-of-the-art Pt/C catalyst. The general ionic salt assisted method is a promising strategy for developing efficient and robust catalysts, electrode materials towards economic platinum-free zinc-air batteries and other energy storage systems.