Potential- and Buffer-Dependent Selectivity for the Conversion of CO 2 to CO by a Cobalt Porphyrin-Peptide Electrocatalyst in Water.

A semisynthetic electrocatalyst for carbon dioxide reduction to carbon monoxide in water is reported. Cobalt microperoxidase-11 (CoMP11-Ac) is shown to reduce CO 2 to CO with a turnover number of up to 32,000 and a selectivity of up to 88:5 CO:H 2 . Higher selectivity for CO production is favored by a less cathodic applied potential and use of a higher p K a buffer. A mechanistic hypothesis is presented in which avoiding the formation and protonation of a formal Co(I) species favors CO production. These results demonstrate how tuning reaction conditions impact reactivity toward CO 2 reduction for a biocatalyst previously developed for H 2 production.