Metallocorroles as Nonprecious-Metal Catalysts for Oxygen Reduction

Naomi Levy, Atif Mahammed, Monica Kosa, Dan T. Major, Zeev Gross,* and Lior Elbaz* 

Angewandte Chemie International Edition

Angew. Chem. Int. Ed. 2015, 54, 1 – 6

Article first published online: 2 OCT 2015

DOI: 10.1002/anie.201505236

http://onlinelibrary.wiley.com/doi/10.1002/anie.201505236/abstract 

Abstract

The future of affordable fuel cells strongly relies on the design of earth-abundant (non-platinum) catalysts for the electrochemical oxygen reduction reaction (ORR). However, the bottleneck in the overall process occurs therein. We have examined herein trivalent Mn, Fe, Co, Ni, and Cu complexes of β-pyrrole-brominated corrole as ORR catalysts. The adsorption of these complexes on a high-surface-area carbon powder (BP2000) created a unique composite material, used for electrochemical measurements in acidic aqueous solutions. These experiments disclosed a clear dependence of the catalytic activity on the metal center of the complexes, in the order of Co>Fe>Ni>Mn>Cu. The best catalytic performance was obtained for the Co^III corrole, whose onset potential was as positive as 0.81 V versus the reversible hydrogen electrode (RHE). Insight into the properties of these systems was gained by spectroscopic and computational characterization of the reduced and oxidized forms of the metallocorroles.