Enzyme-Inspired Iron Porphyrins for Improved Electrocatalytic Oxygen Reduction and Evolution Reactions.
Angew Chem Int Ed Engl
; 60(14): 7576-7581, 2021 03 29.
Article
en En
| MEDLINE
| ID: mdl-33462971
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 160â
mV and a decrease of OER overpotential by 150â
mV to get the benchmark current density at 10â
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.
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