Impact of the Surface Microenvironment on the Redox Properties of a Co-Based Molecular Cathode for Selective Aqueous Electrochemical CO₂-to-CO Reduction

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(22), С. 15345 - 15355

Опубликована: Май 20, 2024

Electrode-confined molecular catalysts are promising systems to enable the efficient conversion of CO2 useful products. Here, we describe development an original cathode for reduction CO based on noncovalent integration a tetraazamacrocyclic Co complex carbon nanotube-based matrix. Aqueous electrochemical characterization modified electrode allowed clear observation change redox behavior center as surface concentration was tuned, highlighting impact catalyst microenvironment its properties. The enabled CO2-to-CO in fully aqueous conditions, giving rise turnover number (TONCO) up 20 × 103 after 2 h constant electrolysis at mild overpotential (η = 450 mV) and with faradaic efficiency about 95%. Post operando measurements using techniques, inductively coupled plasma, X-ray photoelectron spectroscopy absorption films demonstrated that catalysis remained nature, making this Co-based new alternative electrocatalytic media.

Язык: Английский

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Mechanism of Electrochemical Proton Reduction Catalyzed by a Cobalt Tetraaza Schiff Base Macrocyclic Complex: Ligand Protonation and/or Influence of the Chloro Ligand

ACS Catalysis, Год журнала: 2024, Номер 14(15), С. 11352 - 11365

Опубликована: Июль 19, 2024

Cobalt complexes with tetra- and pentaaza-macrocyclic ligands, including the pyridyldiimine motif isolated by Busch as early 1970s, is a very promising family of catalysts that were only quite recently exploited for both electro- photocatalytic HER CO2RR. In particular, tetraaza [CoIII(CR14)Cl2]+ (CR14 = 2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),2,11,13,15-pentaene) appears to be one most efficient stable Co in pure aqueous solution HER. this work, we reinvestigated H2-evolving mechanism catalyzed complex an organic solvent (CH3CN) acid p-cyanoanilinium tetrafluoroborate proton source. By comparison [CoIII(CR14)(CH3CN)2]3+ electrochemical behavior without addition chloride, first characterized thermodynamical coordination decoordination properties chloro ligands at CoIII, CoII, CoI formal redox states. Then, showed (through echem, UV–visible absorption, EPR) facilitates ligand CoII state rather than protonation nitrogen ligand. The electroreduction then kinetically thorough cyclic voltammetry analysis. resting bulk course constant potential electrolysis reduction was identified nonprotonated [CoII(CR14)(CH3CN)x]2+ (x 1 or 2) species, whereas it proposed hydride diffusion-reaction layer.

Язык: Английский

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Low-valent molecular cobalt complexes for CO2 reduction

Advances in catalysis, Год журнала: 2024, Номер unknown, С. 181 - 256

Опубликована: Янв. 1, 2024

Язык: Английский

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