Nanowrinkled Carbon Aerogels Embedded with FeN x Sites as Effective Oxygen Electrodes for Rechargeable Zinc-Air Battery

Ting He; Bingzhang Lu; Yang Chen; Yong Wang; Yaqiang Zhang; John L Davenport; Alan P Chen; Chih-Wen Pao; Min Liu; Zhifang Sun; Alexander Stram; Alexander Mordaunt; Jairo Velasco Jr; Yuan Ping; Yi Zhang; Shaowei Chen

doi:10.34133/2019/6813585

Nanowrinkled Carbon Aerogels Embedded with FeN _x Sites as Effective Oxygen Electrodes for Rechargeable Zinc-Air Battery

Research (Wash D C). 2019 Dec 20:2019:6813585. doi: 10.34133/2019/6813585. eCollection 2019.

Authors

Ting He^{1

2}, Bingzhang Lu², Yang Chen¹, Yong Wang¹, Yaqiang Zhang³, John L Davenport⁴, Alan P Chen⁴, Chih-Wen Pao⁵, Min Liu⁶, Zhifang Sun¹, Alexander Stram⁴, Alexander Mordaunt⁴, Jairo Velasco Jr⁴, Yuan Ping², Yi Zhang^{1

7}, Shaowei Chen²

Affiliations

¹ State Key Laboratory for Powder Metallurgy, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China.
² Department of Chemistry and Biochemistry, University of California, 1156 High Street, Santa Cruz, California 95064, USA.
³ Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 1H9.
⁴ Department of Physics, University of California, 1156 High Street, Santa Cruz, California 95064, USA.
⁵ X-Ray Absorption Group, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
⁶ Institute of Super-Microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University, Changsha 410083, China.
⁷ Key Laboratory of Materials Processing and Mold (Zhengzhou University), Ministry of Education, Zhengzhou 450002, China.

Abstract

Rational design of single-metal atom sites in carbon substrates by a flexible strategy is highly desired for the preparation of high-performance catalysts for metal-air batteries. In this study, biomass hydrogel reactors are utilized as structural templates to prepare carbon aerogels embedded with single iron atoms by controlled pyrolysis. The tortuous and interlaced hydrogel chains lead to the formation of abundant nanowrinkles in the porous carbon aerogels, and single iron atoms are dispersed and stabilized within the defective carbon skeletons. X-ray absorption spectroscopy measurements indicate that the iron centers are mostly involved in the coordination structure of FeN₄, with a minor fraction (ca. 1/5) in the form of FeN₃C. First-principles calculations show that the FeN _x sites in the Stone-Wales configurations induced by the nanowrinkles of the hierarchically porous carbon aerogels show a much lower free energy than the normal counterparts. The resulting iron and nitrogen-codoped carbon aerogels exhibit excellent and reversible oxygen electrocatalytic activity, and can be used as bifunctional cathode catalysts in rechargeable Zn-air batteries, with a performance even better than that based on commercial Pt/C and RuO₂ catalysts. Results from this study highlight the significance of structural distortions of the metal sites in carbon matrices in the design and engineering of highly active single-atom catalysts.