Electrodeposited Films of Manganese–Bipyridine Complexes for Aqueous Electrochemical CO ₂ Reduction

The advancement and innovation of immobilized catalytic systems toward upscaling and improved stability for the efficient reduction of CO2 have been a focal point in electrocatalysis research. Herein, the modification of carbon cloth electrodes is reported through the electropolymerization of a well-studied manganese bipyridine complex. A conjugated, polymeric network of manganese active sites is generated using diazonium ion chemistry, facilitating the conversion of CO2 into highly valued C1 products. Two variations of diamine manganese complexes are investigated by directing the film’s generated aryl radical polymer growth through surface attachment at either the 4,4′- or the 5,5′-substituent position of the respective bipyridine ligand. The functionalized electrodes were characterized via X-ray photoelectron spectroscopy (XPS) and various electrochemical measurements to determine the structure and electronic environment of the covalently anchored complexes. Electrolysis and cyclic voltammetry studies reveal the activity of the manganese devices in aqueous media for the production of syngas (CO and H2) and formate (HCOO¯), achieving turnover numbers (TON) of up to ∼8000 and electrolysis current densities of up to 10 mA/cm2.