Molecular Catalysis of Electrochemical Reactions: Competition between Reduction of the Substrate and Deactivation of the Catalyst by a Cosubstrate Application to N2O Reduction

In the context of molecular catalysis of electrochemical reactions, the competition between reduction of the substrate and deactivation of the catalyst by a cosubstrate is investigated. It is a frequent situation because proton donors are ubiquitous cosubstrates in reductive electrochemical reaction...

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Bibliographic Details
Published in:ChemElectroChem 2021-10, Vol.8 (19), p.3740-3744
Main Authors: Deeba, Rana, Chardon‐Noblat, Sylvie, Costentin, Cyrille
Format: Article
Language:English
Subjects:
Acetonitrile
Catalysis
catalyst deactivation
Catalysts
Chemical reactions
Chemical Sciences
Competition
Coordination compounds
cyclic voltammetry
Deactivation
electrocatalysis
molecular catalysis
Nitrous oxide
nitrous oxide reduction
Protonation
Protons
Substrates
Transition metal compounds
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Summary:In the context of molecular catalysis of electrochemical reactions, the competition between reduction of the substrate and deactivation of the catalyst by a cosubstrate is investigated. It is a frequent situation because proton donors are ubiquitous cosubstrates in reductive electrochemical reactions and molecular catalysts, either transition metal complexes or organic aromatic molecules, and are often prone to electrohydrogenation. We provide a formal kinetic analysis in the framework of cyclic voltammetry, and we show that the response is governed by two parameters and that the competition does not depend on the scan rate. From this analysis a methodology is proposed to analyze such systems and then illustrated via the study of N2O to N2 electroreduction catalyzed by 4‐cyanopyridine in acetonitrile electrolyte with water as proton donor. Incidentally, new insights into the mechanism of 4‐cyanopyridine radical anion protonation are revealed. Homogeneous catalysis of electrochemical reactions allows overcoming overpotential encountered in direct reduction or oxidation. The competition between reduction of the substrate and deactivation of the catalyst by a cosubstrate is however often source of the low durability of the catalysts. This issue is analysed in the framework of cyclic voltammetry and it is illustrated via 4‐cyanopyridine catalysed reduction of N2O to N2 in the presence of water.
ISSN:2196-0216
2196-0216
DOI:10.1002/celc.202101064