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O: Fachverband Oberflächenphysik
O 18: Solid-Liquid Interfaces I: Structure and Spectroscopy
O 18.3: Talk
Monday, March 18, 2024, 15:30–15:45, H 1012
Cu/Au(111) Surfaces and AuCu Intermetallics for Electrocatalytic Reduction of CO2 in Ionic Liquid Electrolytes — •Björn Ratschmeier1, Christian Paulsen1, Klaus Stallberg2, Gina Roß1, Winfried Daum2, Rainer Pöttgen1, and Björn Braunschweig1 — 1University of Münster, Germany — 2TU Clausthal, Germany
Room-temperature ionic liquids (RTIL) are important alternatives for reducing high overpotentials and modifying product selectivities in CO2 reduction reactions (CO2RR). The activity of Au(111), Cu(111), Cu-modified Au(111) electrodes, and AuCu intermetallics in contact with 1-butyl-3-methylimidazolium trifluorosulfonylimide [BMIM][NTf2] electrolytes was investigated in terms of CO2RR. In operando IR absorption spectroscopy (IRAS) of the bulk electrolyte reveals the formation of a 2-imidazolium carboxylic acid intermediate that can lower the overpotential for CO2RR and does not require stabilization of the CO2 radical anion as an alternative intermediate at the interface. On Au(111) we observe the formation of H2 and mainly CO, while on Cu(111) the only reduction product is H2. By systematically varying the copper content at the catalyst surfaces, we are able to tune the H2/CO syngas ratio to a maximum of 1.8 for Cu-modified Au(111) electrodes and 3.2 for AuCu3 catalysts, demonstrating a large tunability of the syngas ratio with electrode potential. The observed H2/CO ratios approach the ideal value of 2 needed for the Fischer-Tropsch process and a ratio of 3 required for methanation.
Keywords: CO2 electroreduction; ionic liquids; gold electrodes; copper electrodes; intermetallic catalyst