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Bimetallic porous porphyrin polymer-derived non-precious metal electrocatalysts for oxygen reduction reactions

Brüller, Sebastian and Liang, Hai-Wei and Kramm, Ulrike I. and Krumpfer, Joseph W. and Feng, Xinliang and Müllen, Klaus (2015):
Bimetallic porous porphyrin polymer-derived non-precious metal electrocatalysts for oxygen reduction reactions.
In: J. Mater. Chem. A, The Royal Societys of chemistry, pp. 23799-23808, 3, (47), ISSN 2050-7488, [Online-Edition: http://dx.doi.org/10.1039/C5TA06309D],
[Article]

Abstract

The development of efficient and stable electrocatalysts on the basis of non-precious metals (Co, Fe) is considered as one of the most promising routes to replace expensive and susceptible platinum as the oxygen reduction reaction (ORR) catalyst. Here we report a synthetic strategy for the precursor controlled, template-free preparation of novel mono- (Fe; Co) and bimetallic (Fe/Co) nitrogen-doped porous carbons and their electrocatalytic performance towards the ORR. The precursors are composed of metal–porphyrin based conjugated microporous polymers (M-CMPs with M = Fe; Co; Fe/Co) derived from polymerization of metalloporphyrins by the Suzuki polycondensation reaction, which enables the synthesis of bimetallic polymers with alternating metal–porphyrin units for the preparation of carbon-based catalysts with homogenously distributed CoN4 and FeN4 centres. Subsequent pyrolysis of the networks reveals the key role of pre-morphology and network composition on the active sites. 57Fe-Mössbauer spectroscopy was conducted on iron catalysts (Fe; Fe/Co) to determine the coordination of Fe within the N-doped carbon matrix and the catalytic activity-enhancing shift in electron density. In acidic media the bimetallic catalyst demonstrates a synergetic effect for cobalt and iron active sites, mainly through a 4-electron transfer process, achieving an onset potential of 0.88 V (versus a reversible hydrogen electrode) and a half-wave potential of 0.78 V, which is only 0.06 V less than that of the state-of-the-art Pt/C catalyst.

Item Type: Article
Erschienen: 2015
Creators: Brüller, Sebastian and Liang, Hai-Wei and Kramm, Ulrike I. and Krumpfer, Joseph W. and Feng, Xinliang and Müllen, Klaus
Title: Bimetallic porous porphyrin polymer-derived non-precious metal electrocatalysts for oxygen reduction reactions
Language: English
Abstract:

The development of efficient and stable electrocatalysts on the basis of non-precious metals (Co, Fe) is considered as one of the most promising routes to replace expensive and susceptible platinum as the oxygen reduction reaction (ORR) catalyst. Here we report a synthetic strategy for the precursor controlled, template-free preparation of novel mono- (Fe; Co) and bimetallic (Fe/Co) nitrogen-doped porous carbons and their electrocatalytic performance towards the ORR. The precursors are composed of metal–porphyrin based conjugated microporous polymers (M-CMPs with M = Fe; Co; Fe/Co) derived from polymerization of metalloporphyrins by the Suzuki polycondensation reaction, which enables the synthesis of bimetallic polymers with alternating metal–porphyrin units for the preparation of carbon-based catalysts with homogenously distributed CoN4 and FeN4 centres. Subsequent pyrolysis of the networks reveals the key role of pre-morphology and network composition on the active sites. 57Fe-Mössbauer spectroscopy was conducted on iron catalysts (Fe; Fe/Co) to determine the coordination of Fe within the N-doped carbon matrix and the catalytic activity-enhancing shift in electron density. In acidic media the bimetallic catalyst demonstrates a synergetic effect for cobalt and iron active sites, mainly through a 4-electron transfer process, achieving an onset potential of 0.88 V (versus a reversible hydrogen electrode) and a half-wave potential of 0.78 V, which is only 0.06 V less than that of the state-of-the-art Pt/C catalyst.

Journal or Publication Title: J. Mater. Chem. A
Volume: 3
Number: 47
Publisher: The Royal Societys of chemistry
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Catalysts and Electrocatalysts
07 Department of Chemistry
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 01 Mar 2016 09:34
Official URL: http://dx.doi.org/10.1039/C5TA06309D
Identification Number: doi:10.1039/C5TA06309D
Funders: This work was financially supported by the Max Planck Society through the program MaxNet Energy, ERC grant on NANOGRAPH, the project INSOLCELL and EC Graphene Flagship (CNECT-ICT-604391)., Financial support by the DFG funding of the Excellence Initiative, Darmstadt Graduate School of Excellence Energy Science and Engineering (GSC 1070) is gratefully acknowledged by UIK.
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