Electrocatalytic reduction of dioxygen by Mn(iii) meso-tetra(N-methylpyridinium-4-yl)porphyrin in universal buffer.

The electrochemical characterization of manganese(iii) meso-tetra(N-methylpyridinium-4-yl)porphyrin pentachloride ([Mn(TMPyP)Cl][Cl]) via cyclic voltammetry (CV) and UV-vis spectroelectrochemistry (UV-vis SEC) was performed across the entire pH domain in aqueous buffered conditions. Assessment of the homogeneous electrocatalytic efficiency for the oxygen reduction reaction (ORR) from pH 3 to 6 using rotating-ring disk electrode experiments (RRDE) found it to be selective for water (82 to 93%). The observed efficiency for water is in contrast to previous reports on electrocatalytic ORR activity by Mn porphyrins in aqueous systems, which identified HO as the primary product using indirect RDE methods only.

Metal-Free Electrochemical Reduction of Carbon Dioxide Mediated by Cyclic(Alkyl)(Amino) Carbenes.

Carbenes are known to activate carbon dioxide to form zwitterionic adducts. Their inherent metal-free redox activity remains understudied. Herein, we demonstrate that zwitterionic adducts of carbon dioxide formed with cyclic(alkyl)(amino) carbenes are not only redox active, but they can mediate the stoichiometric reductive disproportionation of carbon dioxide to carbon monoxide and carbonate.