Molecular Cobalt Complexes with Pendant Amines for Selective Electrocatalytic Reduction of Carbon Dioxide to Formic Acid

Roy, Souvik, Sharma, Bhaskar, Pécaut, Jacques , Simon, Philippe, Fontecave, Marc, Tran, Phong D., Derat, Etienne and Artero, Vincent (2017) Molecular Cobalt Complexes with Pendant Amines for Selective Electrocatalytic Reduction of Carbon Dioxide to Formic Acid. Journal of the American Chemical Society, 139 (10). pp. 3685-3696. ISSN 0002-7863

Full content URL: https://doi.org/10.1021/jacs.6b11474

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Item Type:Article
Item Status:Live Archive

Abstract

We report here on a new series of CO2-reducing molecular catalysts based on Earth-abundant elements that are very selective for the production of formic acid in dimethylformamide (DMF)/water mixtures (Faradaic efficiency of 90 ± 10%) at moderate overpotentials (500–700 mV in DMF measured at the middle of the catalytic wave). The [CpCo(PR2NR′2)I]+ compounds contain diphosphine ligands, PR2NR′2, with two pendant amine residues that act as proton relays during CO2-reduction catalysis and tune their activity. Four different PR2NR′2 ligands with cyclohexyl or phenyl substituents on phosphorus and benzyl or phenyl substituents on nitrogen were employed, and the compound with the most electron-donating phosphine ligand and the most basic amine functions performs best among the series, with turnover frequency >1000 s–1. State-of-the-art benchmarking of catalytic performances ranks this new class of cobalt-based complexes among the most promising CO2-to-formic acid reducing catalysts developed to date; addressing the stability issues would allow further improvement. Mechanistic studies and density functional theory simulations confirmed the role of amine groups for stabilizing key intermediates through hydrogen bonding with water molecules during hydride transfer from the Co center to the CO2 molecule.

Keywords:Organic acids, Redox reactions, Amines, Catalysts, Electrolysis
Subjects:F Physical Sciences > F100 Chemistry
F Physical Sciences > F161 Organometallic Chemistry
Divisions:College of Science > School of Chemistry
ID Code:40669
Deposited On:17 Apr 2020 12:07

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