Regensburg 2025 – scientific programme

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O: Fachverband Oberflächenphysik

O 34: Poster Solid-Liquid Interfaces: Reactions and Electrochemistry

O 34.5: Poster

Tuesday, March 18, 2025, 13:30–15:30, P3

Electrocatalytic CO2 Reduction in Ionic Liquid/Nitrile Electrolytes — •Björn Ratschmeier, Arik Geringswald, Alisa Kamaric, and Björn Braunschweig — University Münster, Institute of Physical Chemistry, Münster, Germany

Room-temperature ionic liquids (RTILs) play an important role in CO2 reduction reactions (CO2RR), providing a viable alternative to aqueous electrolytes, but face challenges such as high overpotentials and product selectivity. As we have previously shown for 1-butyl-3-methylimidazolium trifluorosulfonylimide ([BMIM][NTf2]) electrolytes [1], the accessibility of water as a co-reactant at the interface is a limiting factor for CO formation potentials. To modulate the interfacial structure, different concentrations of acetonitrile and benzonitrile were introduced into [BMIM][NTf2] electrolytes in the presence of 1.5 M H2O. The resulting mixtures were investigated in terms of CO2RR at polycrystalline Au electrodes. The presence of 7.5 M benzonitrile resulted in a 20-fold increase in CO formation, and in even higher CO concentrations with acetonitrile compared to the pure ionic liquid. Consequently, we propose that nitrile additives tune the interfacial structure in such a way that the access of water molecules is improved. In order to validate this hypothesis, we aim for an in-depth investigation of the bulk electrolyte as well as of the interfacial structure using in situ IR and SFG spectroscopy. [1] Ratschmeier et al. Electrochem. Sci. Adv. 2023, 3, e2100173.

Keywords: Electrocatalysis; CO2 Reduction; Ionic Liquids; SFG spectroscopy; IR spectroscopy