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Enzyme-Inspired Iron Porphyrins for Improved Electrocatalytic Oxygen Reduction and Evolution Reactions

 
: Xie, L.; Zhang, X.-P.; Zhao, B.; Li, P.; Qi, J.; Guo, X.; Wang, B.; Lei, H.; Zhang, W.; Apfel, U.-P.; Cao, R.

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Angewandte Chemie. International edition 60 (2021), Nr.14, S.7576-7581
ISSN: 1433-7851
ISSN: 0044-8249
ISSN: 0570-0833
ISSN: 1521-3773
Englisch
Zeitschriftenaufsatz
Fraunhofer UMSICHT Oberhausen ()

Abstract
Nature uses Fe porphyrin sites for the oxygen reduction reaction (ORR). Synthetic Fe porphyrins have been extensively studied as ORR catalysts, but activity improvement is required. On the other hand, Fe porphyrins have been rarely shown to be efficient for the oxygen evolution reaction (OER). We herein report an enzyme-inspired Fe porphyrin 1 as an efficient catalyst for both ORR and OER. Complex 1, which bears a tethered imidazole for Fe binding, beats imidazole-free analogue 2, with an anodic shift of ORR half-wave potential by 160 mV and a decrease of OER overpotential by 150 mV to get the benchmark current density at 10 mA cm−2. Theoretical studies suggested that hydroxide attack to a formal FeV=O form the O−O bond. The axial imidazole can prevent the formation of trans HO-FeV=O, which is less effective to form O−O bond with hydroxide. As a practical demonstration, we assembled rechargeable Zn-air battery with 1, which shows equal performance to that with Pt/Ir-based materials.

: http://publica.fraunhofer.de/dokumente/N-636891.html