Hierarchically assembled cobalt oxynitride and N-doped carbon nanofiber hybrids for efficient bifunctional oxygen electrocatalysis with exceptional regenerative efficiency

Title
Hierarchically assembled cobalt oxynitride and N-doped carbon nanofiber hybrids for efficient bifunctional oxygen electrocatalysis with exceptional regenerative efficiency
Authors
채근화김형준김진영박현서김종민임아연이경아김승훈채지언김준황창규윤기로정지원조수호Jitendra Pal Singh신기현문병무함형철김일두
Issue Date
2021-07
Publisher
ACS Nano
Citation
VOL 15-11230
Abstract
Oxygen-based electrocatalysis is an integral aspect of a clean and sustainable energy conversion/storage system. The development of economic bifunctional electrocatalysts with high activity and durability during reversible reactions remains a great challenge. The tailored porous structure and separately presented active sites for oxygen reduction and oxygen evolution reactions (ORR and OER) without mutual interference are most crucial for achieving desired bifunctional catalysts. Here, we report a hybrid composed of sheath-core cobalt oxynitride (CoOx@CoNy) nanorods grown perpendicularly on N-doped carbon nanofiber (NCNF). The brush-like CoOx@CoNy nanorods, composed of metallic Co4N cores and oxidized surfaces, exhibit excellent OER activity (E = 1.69 V at 10 mA cm-2) in an alkaline medium. Although pristine NCNF or CoOx@CoNy alone had poor catalytic activity in the ORR, the hybrid showed dramatically enhanced ORR performance (E = 0.78 V at -3 mA cm-2). The experimental results coupled with a density functional theory (DFT) simulation confirmed that the broad surface area of the CoOx@CoNy nanorods with an oxidized skin layer boosts the catalytic OER, while the facile adsorption of ORR intermediates and a rapid interfacial charge transfer occur at the interface between the CoOx@CoNy nanorods and the electrically conductive NCNF. Furthermore, it was found that the independent catalytic active sites in the CoOx@CoNy/NCNF catalyst are continuously regenerated and sustained without mutual interference during the round-trip ORR/OER, affording stable operation of Zn-air batteries.
URI
http://pubs.kist.re.kr/handle/201004/73846
ISSN
1936-0851
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KIST Publication > Article
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