Dresden 2026 – scientific programme

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O: Fachverband Oberflächenphysik

O 25: Solid-liquid interfaces: Structure, spectroscopy – Poster

O 25.1: Poster

Monday, March 9, 2026, 18:00–20:00, P2

Role of Interfacial Water for CO2 Reduction Reactions in Ionic Liquid/Acetonitrile Electrolytes — •Björn Ratschmeier¹, Arik Geringswald¹, Alisa Kamaric¹, Angel Cuesta², and Björn Braunschweig¹ — ¹University of Münster, Institute of Physical Chemistry, Münster, Germany — ²Advanced Centre for Energy and Sustainability (ACES), School of Natural and Computing Sciences, University of Aberdeen, UK

Room-temperature ionic liquids (RTILs) such as 1-butyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide ([BMIM][NTf2]) are promising electrolytes for CO2 reduction reaction (CO₂RR), where the availability of water at the electrode/electrolyte interface is known to play a decisive role in the reaction mechanism. We find that the addition of acetonitrile (ACN) to [BMIM][NTf2] with 1.5 M H₂O markedly increases the CO yield, while the onset potential for CO formation remains essentially unchanged. In situ IRAS of bulk intermediates formed during CO₂RR are indicative for a reaction pathway [1] via a [BMIM]-COOH intermediate that requires the presence of interfacial H₂O as shown in previous work. In contrast, in situ ATR-SEIRAS reveals ACN-induced modifications of the electrode/electrolyte interface. OH vibrational bands increase significantly at cathodic potentials, indicating enhanced water accumulation at the interface, thus, causing larger availability of water for CO2RR. Ref.: [1] Ratschmeier et al. ACS Catalysis 14, 1773 (2024).

Keywords: Electrocatalysis; CO2 Reduction; Ionic Liquids; ATR-SEIRAS; IR spectroscopy