Immobilizing single atom catalytic sites onto highly reduced carbon hosts: Fe–N 4 /CNT as a durable oxygen reduction catalyst for Na–air batteries

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2020-09, Vol.8 (36), p.18891-18902
• Main Authors: Noh, Woo Yeong, Kim, Eun Mi, Kim, Kwang Young, Kim, Jin Hyun, Jeong, Hu Young, Sharma, Pankaj, Lee, Geunsik, Jang, Ji-Wook, Joo, Sang Hoon, Lee, Jae Sung
• Format: Article
• Language: English
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/D0TA06489K

Immobilizing metal ions on a carbon support usually involves severe aggregation (sintering) and loose attachment of metal ions owing to a weak metal–support interaction. Here, we propose an alternative synthetic strategy termed ‘selective microwave annealing’ (SMA) to stabilize abundant single atom catalytic sites onto a highly reduced form of carbon host with only a few minutes of microwave irradiation. Thus, nitrogen-coordinated single atom iron sites on a carbon nanotube (Fe–N 4 /CNT) synthesized via SMA show unprecedented oxygen reduction reaction (ORR) activity and pH-universal durability superior to those of thermally annealed Fe–N 4 /CNT and expensive Pt/C catalysts. Furthermore, an aqueous Na–air battery with our Fe–N 4 /CNT catalyst operates as effectively as the device with the Pt/C catalyst. The method provides a new concept for the design of various strongly coupled and highly dispersed carbon-supported catalysts, which could open up new avenues for use in a wide range of electrochemical and catalytic applications.