Potential- and Buffer-Dependent Selectivity for the Conversion of CO2to CO by a Cobalt Porphyrin-Peptide Electrocatalyst in Water

Abstract

A semisynthetic electrocatalyst for carbon dioxide reduction to carbon monoxide in water is reported. Cobalt microperoxidase-11 (CoMP11-Ac) is shown to reduce CO2 to CO with a turnover number of up to 32,000 and a selectivity of up to 88:5 CO:H2. Higher selectivity for CO production is favored by a less cathodic applied potential and use of a higher pKa 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 CO2 reduction for a biocatalyst previously developed for H2 production.