Electrocatalytic CO2 Reduction

Monitoring of Catalytically Active, Downgraded, and Upgraded Cobalt Complexes

Journal Article (2024)
Author(s)

Abhinav Bairagi (Radboud Universiteit Nijmegen)

Aleksandr Y. Pereverzev (Radboud Universiteit Nijmegen)

Paul Tinnemans (Radboud Universiteit Nijmegen)

Evgeny Pidko (TU Delft - ChemE/Inorganic Systems Engineering)

Jana Roithová (Radboud Universiteit Nijmegen)

Research Group
ChemE/Inorganic Systems Engineering
DOI related publication
https://doi.org/10.1021/jacs.3c13290
More Info
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Publication Year
2024
Language
English
Research Group
ChemE/Inorganic Systems Engineering
Issue number
8
Volume number
146
Pages (from-to)
5480-5492

Abstract

The premise of most studies on the homogeneous electrocatalytic CO2 reduction reaction (CO2RR) is a good understanding of the reaction mechanisms. Yet, analyzing the reaction intermediates formed at the working electrode is challenging and not always attainable. Here, we present a new, general approach to studying the reaction intermediates applied for CO2RR catalyzed by a series of cobalt complexes. The cobalt complexes were based on the TPA-ligands (TPA = tris(2-pyridylmethyl)amine) modified by amino groups in the secondary coordination sphere. By combining the electrochemical experiments, electrochemistry-coupled electrospray ionization mass spectrometry, with density functional theory (DFT) calculations, we identify and spectroscopically characterize the key reaction intermediates in the CO2RR and the competing hydrogen-evolution reaction (HER). Additionally, the experiments revealed the rarely reported in situ changes in the secondary coordination sphere of the cobalt complexes by the CO2-initiated transformation of the amino substituents to carbamates. This launched an even faster alternative HER pathway. The interplay of three catalytic cycles, as derived from the experiments and supported by the DFT calculations, explains the trends that cobalt complexes exhibit during the CO2RR and HER. Additionally, this study demonstrates the need for a molecular perspective in the electrocatalytic activation of small molecules efficiently obtained by the EC-ESI-MS technique.

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