Enzyme‐Inspired Iron Porphyrins for Improved Electrocatalytic Oxygen Reduction and Evolution Reactions. (26th February 2021)

• Record Type: Journal Article
• Authors: Xie, Lisi; Zhang, Xue‐Peng; Zhao, Bin; Li, Ping; Qi, Jing; Guo, Xinai; Wang, Bin; Lei, Haitao; Zhang, Wei; Apfel, Ulf‐Peter; Cao, Rui
• Is Part Of: Angewandte Chemie. Volume 133:Number 14(2021)
• Page Start: 7654
• Page End: 7659
• Publication Date: 2021-02-26
• Subjects: catalyst design -- metal-air battery -- molecular electrocatalysis -- oxygen evolution -- oxygen reduction; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202015478
• Languages: English
• ISSNs: 0044-8249

Abstract

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 Fe V =O form the O−O bond. The axial imidazole can prevent the formation of trans HO‐Fe V =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. Abstract : An enzyme‐inspired Fe porphyrin with a tethered imidazole is synthesized and beats its imidazole‐free analogue for electrocatalytic ORR and OER. By presenting state‐of‐the‐art molecular catalytic features, Zn‐air batteries with this Fe porphyrin show equal performance to batteries with Pt/C‐Ir/C. This work underlines unique benefits and promising applications of molecular electrocatalysis in new energy conversion technologies.