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

Nandan, Ravi and Gautam, Ajay and Tripathi, Shalini and Nanda, Karuna Kar (2018) A comprehensive analysis and rational designing of efficient Fe-based oxygen electrocatalysts for metal-air batteries. In: JOURNAL OF MATERIALS CHEMISTRY A, 6 (18). pp. 8537-8548.

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Official URL: https://dx.doi.org/10.1039/c8ta01938j

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 similar to 93 and similar to 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 Delta E (= E-j(OER) = 10 - E-1/2(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.

Item Type: Journal Article
Additional Information: Copy right of this article belong to ROYAL SOC CHEMISTRY, THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND
Department/Centre: Division of Chemical Sciences > NMR Research Centre (Formerly Sophisticated Instruments Facility)
Depositing User: Id for Latest eprints
Date Deposited: 27 Jun 2018 17:46
Last Modified: 27 Jun 2018 17:46
URI: http://eprints.iisc.ac.in/id/eprint/60094

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