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Communication Dans Un Congrès Année : 2021

Ionic liquids’s Co-catalytic Effect on Electrochemical CO2 Reduction Mediated by Model Molecular Catalysts

Résumé

The use of Ionic Liquids (ILs) has proven to enhance carbon dioxide (CO2) electroreduction, while their inherent conductivity and large electrochemical windows has sparked investigation in their use as a solvent and/or supporting electrolyte.1 However, the high viscosity values of ILs that hinder mass transfer and cause lower currents2 deterred us from using ILs as the solvent in the present study, in which we opted instead for binary mixtures of ILs and acetonitrile. While the role of ILs in heterogeneous catalysis has been extensively addressed, little study has been devoted to the elucidation of their role in the context of molecular electrocatalysis for CO2 reduction.3 In this study we evaluate the role of ILs in the case of CO2 electroreduction by a molecular catalyst and for this purpose we selected the well-established [Re(CO)3bpyCl] complex, also known as Lehn’s catalyst, because of its high selectivity for CO production, as well as its fully elaborated mechanism. To this effect, a series of 5 ILs were chosen, belonging to the imidazolium and pyrrolidinium cation families. Each of those ILs, at a concentration of 0.5M in acetonitrile was studied in presence of the rhenium catalyst initially by cyclic voltammetry and subsequently by controlled potential electrolysis experiments. According to our results, the presence of the IL under CO2 catalytic conditions was enough to cause a shift in the CO2 electroreduction overpotential of about 330mV, proving the existence of a co-catalystic role of the IL for the system, though this effect was less pronounced when an external proton source was added.4 Moreover, a mechanistic explanation of the IL effect is proposed, evoking the electrostatic stabilization of the negatively-charged intermediates of the catalyst by the IL cations and in the case of imidazolium cations, stabilization through π-π stacking, a characteristic that could explain their superior performance. References: (1) Sánchez-Sánchez, C. M.; Encyclopedia of Interfacial Chemistry : Surface Science and Electrochemistry; Wandelt, K., Ed.; Elsevier, 2018, p 539–551. (2) Grills, D. C.; Matsubara, Y.; Kuwahara, Y.; Golisz, S. R.; Kurtz, D. A.; Mello, B. A. J. Phys. Chem. Lett. 2014, 5 (11), 2033–2038. (3) Choi, J.; Benedetti, T. M.; Jalili, R.; Walker, A.; Wallace, G. G.; Officer, D. L. Chem. - Eur. J. 2016, 22 (40), 14158–14161. (4) Vichou, E.; Li, Y.; Gomez-Mingot, M.; Fontecave, M.; Sánchez-Sánchez, C.M. J. Phys. Chem. C, 2020, 124, 43, 23764–23772

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Dates et versions

hal-04028462 , version 1 (14-03-2023)

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  • HAL Id : hal-04028462 , version 1

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Elli Vichou, Yun Xu-Li, Maria Gomez-Mingot, Marc Fontecave, Carlos M Sánchez-Sánchez. Ionic liquids’s Co-catalytic Effect on Electrochemical CO2 Reduction Mediated by Model Molecular Catalysts. ELCOREL 2021 on-line, Universiteit Leiden, Mar 2021, LEIDEN on line, Netherlands. ⟨hal-04028462⟩
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