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Abstract Tetrapyrrolic containing metal complexes are among the most efficient molecular catalysts for the CO 2 reduction. Metalloporphyrins and phthalocyanines are currently under investigations and their catalytic properties are among the best molecular catalysts. Corrole, a contracted tetrapyrrolic macrocycle has been also used to design molecular for the CO 2 reduction. The electrochemical activity towards CO 2 reduction can rival those of their porphyrin analogues. However, the catalytic activity of the metallocorrole is initiated at the corresponding M II/I couple. Accordingly, a catalytic current in presence of CO 2 with cobalt corrole appears when the Co I species is generated. We have designed an electron deficient A 2 B corrole holding two −CF 3 groups and a benzonitrile in the meso positions and its cobalt complex ( 1 ). We reasoned that these groups could shuffle the redox potentials to reach the M(I) oxidation states at more positive values thereby lowering the overpotential for the catalytic CO 2 reduction. Our results clearly show that catalyst 1 when adsorbed on a carbon electrode, shows the most favourable catalytic performance for CO production, achieving an efficiency of 85 % with a current density of −1.5 mA cm −2 at −1.0 V vs NHE. The current densities of controlled potential electrolysis with increasing amount of KHCO 3 , were found to increase more than one order of magnitude with the formation of MeOH.
Zhang et al. (Fri,) studied this question.