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Issue 18, 2018
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A comprehensive analysis and rational designing of efficient Fe-based oxygen electrocatalysts for metal–air batteries

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Abstract

Precious metal based electrocatalysts are considered as the most efficient ones to drive kinetically sluggish oxygen evolution/reduction reactions (OER/ORR) for metal–air batteries and fuel-cells. However, their monofunctionality in addition to their exorbitant cost has stimulated the quest for economically viable bifunctional electrocatalysts for use in next generation electrochemical energy devices. Here, we report Fe–Fe3C encapsulated in Fe–Nx enriched spheres of N-doped carbon nanotubes (FCMR, M = 3, 10, 25, 40 represents the ramping rate of temperature during synthesis) as a potentially enduring, cost effective, highly efficient bifunctional electrocatalyst for total oxygen electrochemistry (ORR and OER) and a comprehensive study to elucidate the role of various Fe moieties. In addition to the improved OER/ORR activities as evident from the better onset potential, lower Tafel slopes and high current densities over commercially available RuO2/Pt–C electrocatalysts and several recently reported state-of-the-art bi-functional electrocatalysts, FC10R shows a current retention value of ∼93 and ∼98% after the accelerated cyclic stability test for the OER and ORR, respectively. The preferable 4e pathways and suppressed peroxide generation in the ORR by FC10R further ensure maximum electrochemical energy harvesting. Remarkably, the complete oxygen electrochemistry of FC10R in alkaline medium as evaluated from ΔE (=Ej(OER) = 10E1/2(ORR) = 0.758 V) is significantly lower than that of commercially available/recently reported electrocatalysts and advocates the minimum cyclic loss. The overall study elucidates the synergistic effect of Fe–Nx coordination and Fe3C moieties on oxygen electrochemistry, and FC10R has shown its potential to serve as a non-precious metal based bifunctional electrocatalyst for next generation electrochemical energy conversion and storage devices. Finally, a prototype Al–air battery arrangement using FC10R as an air-cathode for powering a green light emitting diode has been demonstrated.

Graphical abstract: A comprehensive analysis and rational designing of efficient Fe-based oxygen electrocatalysts for metal–air batteries

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Publication details

The article was received on 28 Feb 2018, accepted on 05 Apr 2018 and first published on 06 Apr 2018


Article type: Paper
DOI: 10.1039/C8TA01938J
Citation: J. Mater. Chem. A, 2018,6, 8537-8548
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    A comprehensive analysis and rational designing of efficient Fe-based oxygen electrocatalysts for metal–air batteries

    R. Nandan, A. Gautam, S. Tripathi and K. K. Nanda, J. Mater. Chem. A, 2018, 6, 8537
    DOI: 10.1039/C8TA01938J

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