Volume 11, Issue 15 p. 2569-2578
Full Paper

Iridium-Coordinated Histidyl Bolaamphiphile Self-Assemblies as Heterogeneous Catalysts for Water Oxidation

Changjoon Keum

Changjoon Keum

Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722 Korea

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Dr. Sang-Yup Lee

Corresponding Author

Dr. Sang-Yup Lee

Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722 Korea

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First published: 06 June 2018
Citations: 8

Graphical Abstract

Whole lotta histidine: Ir-coordinated histidyl bolaamphiphile self-assemblies displayed remarkable catalytic oxygen evolution activity with CeIV as a sacrificial oxidant. IrIII ions coordinated with surface-exposed histidine imidazoles to build multiple catalytic active sites.

Abstract

Catalysts that can promote oxygen evolution from water are necessary for green energy production. In this study, colloidal heterogeneous catalysts for oxygen evolution were prepared by coordination of Ir species to self-assemblies of histidyl bolaamphiphiles. When dissolved in water, the histidyl bolaamphiphiles self-assembled to form particulate structures with the exposure of densely packed histidine imidazoles on their surface. Subsequent coordination of the Ir species to the bolaamphiphile assembly gave rise to catalytic activity toward the oxygen evolution reaction. The oxygen evolution was examined by using the catalytic assemblies in the presence of a sacrificial oxidant, cerium ammonium nitrate. The Ir-coordinated assemblies showed a turnover frequency of 13 min−1, which was comparable to those previously reported for molecular water oxidation catalysts. The catalytic activity increased with increasing histidine imidazole/Ir molar ratio, which suggested that multiple coordination of Ir to imidazoles facilitated the formation of active Ir intermediates. This study demonstrates the feasibility of constructing catalytically active interfaces from colloidal bolaamphiphile assemblies with biochemical ligands.

Conflict of interest

The authors declare no conflict of interest.