Water Oxidation Catalysis by Mono- and Binuclear Iron Corroles

Considering the overwhelming importance and involvement of iron in numerous biocatalytic processes, the scarceness of synthetic iron complexes as water oxidation catalysts (WOCs) is highly surprising. Given the increasing interest in metallocorroles as electrocatalysts, the current study addressed the water-oxidizing ability of mononuclear and two types of binuclear iron corroles: μ-oxo bridged and linked through β-pyrrole C atoms. This disclosed the modulation of electronic factors for lowering the electrochemical onset potential for water oxidation by the monomeric iron corroles and the fact that the C–C-linked dimer outperforms both the monomer and the μ-oxo dimer as a WOC. Parallel investigations on the corresponding bis-cobalt dimer uncovered it to be the best catalyst not only in terms of efficacy but also with regard to the stability of the catalytically active species. The electrode-adsorbed iron corrole is shown to be a good WOC, at a relatively low voltage with a very high Faradaic efficacy.