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2018_01_05_MS_CNTCoNi_HER.pdf (8.94 MB)
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Apically Dominant Mechanism for Improving Catalytic Activities of N-Doped Carbon Nanotube Arrays in Rechargeable Zinc-Air Battery

preprint
submitted on 05.01.2018 and posted on 08.01.2018 by Jose Mendoza-Cortes, Wenhan Niu, Srimanta Pakhira, Kyle Marcus, Zhao Li, Yang Yang

The oxygen reduction (ORR) and oxygen evolution reactions (OER) in Zn-air batteries (ZABs) require highly efficient, cost-effective and stable electrocatalysts as replacements to traditionally high cost, inconsistently stable and low poison resistant Platinum group metals (PGM) catalysts. Although, nitrogen-doped carbon nanotube (NCNT) arrays have been developed over recent decades through various advanced technologies are now capable of catalyzing ORR efficiently, their underdeveloped bifunctional property, hydrophobic surface, and detrimental preparation strategy are found to limit practical large-scale commercialization for effective rechargeable ZABs. Here, we have demonstrated fabrication of a three-dimensional (3D) nickel foam supported NCNT arrays with CoNi nanoparticles (NPs) encapsulated within the apical domain (denoted as CoNi@NCNT/NF) that exhibits excellent bifunctional catalytic performance toward both ORR (onset potential of 0.97 V vs. RHE) and OER (overpotential of 1.54 V vs. RHE at 10 mA cm-2). We further examined the practicability of this CoNi@NCNT/NF material being used as an air electrode for rechargeable ZAB coin cell and pouch cell systems. The ZAB coin cell showed a peak power density of 108 mW cm-2 with an energy density of 845 Wh kgZn-1 and robust rechargeability over 28h under ambient conditions, which exceeds the performance of PGM catalysts and leading non-PGM electrocatalysts. In addition, density functional theory (DFT) calculations revealed that the ORR and OER catalytic performance of the CoNi@NCNT/NF electrode are mainly derived from the d-orbitals from the CoNi NPs encapsulated within the apical dominant end of the NCNTs.

History

Topic

  • Electrocatalysis

Email Address of Submitting Author

mendoza@eng.famu.fsu.edu

Email Address(es) for Other Author(s)

yang.yang@ucf.edu

Institution

University of Central Florida, Florida State University

Country

USA

ORCID For Submitting Author

0000-0001-5184-1406

Declaration of Conflict of Interest

No conflict of interest

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