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

Abstract

The precious metal based electrocatalysts are considered as most efficient ones to drive kinetically sluggish oxygen evolution/reduction reactions (OER/ORR) for metal-air batteries and fuel-cells. However, the monofunctionality in addition to cost offensiveness has stimulated quest for economically viable bifunctional electrocatalysts to serve the 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 potential 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 moities. In addition to the improved OER/ORR activities as evident by better onset potential, lower Tafel slopes and high current densities over the commercially available RuO2/Pt-C electrocatalysts and several recently reported state-of-the-art bi-functional electrocatalysts, FC10R shows a current retention value nearly ~93 and ~98 % after accelerated cyclic stability test for OER and ORR, respectively. The preferably 4e- pathways and suppressed peroxide generation in ORR by FC10R further ensures the maximum electrochemical energy harvesting. Remarkably, the complete oxygen electrochemistry on FC10R in alkaline medium as evaluated by ΔE (=Ej(OER)=10 - E1/2(ORR)=0.758 V) is significantly lower than the 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 in oxygen electrochemistry and FC10R has shown its potential to serve as a non-precious metal based bifunctional electrocatalysts 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.

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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, Accepted Manuscript
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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, Accepted Manuscript , DOI: 10.1039/C8TA01938J

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