Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 38: Solid-Liquid Interfaces 4: Reactions and Electrochemistry

O 38.7: Vortrag

Mittwoch, 7. September 2022, 12:15–12:30, H4

Are organic solvents key to enable CO₂ electro-reduction on Mo₂C as promised in theory? — •Thomas Mairegger¹, Christoph Grießer¹, Haobo Li², Nicolas Hörmann³, Karsten Reuter³, and Julia Kunze-Liebhäuser¹ — ¹Department of Physical Chemistry, Innsbruck, Austria — ²University of Adelaide, Adelaide, Australia — ³Fritz Haber Institute, Berlin, Germany

It has been proposed in active-site computational screening studies that Mo₂C is an effective electrocatalyst for the electrochemical CO₂ reduction reaction (CO₂RR) to valuable fuels, such as hydrocarbons and alcohols. However, the competing hydrogen evolution reaction (HER) has been found to exclusively take place.[1] Reason for this is the formation of a surface oxide film upon air exposure or immersion of Mo₂C into aqueous electrolytes that impedes the formation of the desired higher reduction products.[1]

Here we investigate the CO₂RR activity of polycrystalline hexagonal Mo₂C in non-aqueous electrolyte to avoid passivation of the electrode and circumvent the high HER activity. We show that Mo₂C is capable of reducing CO₂ in reasonable amounts in an acetonitrile electrolyte, with an onset at -1.08 V_SHE.[1] The nature of the products, among them gaseous CO, depends on the concentration of water in the electrolyte. Furthermore, we show that the acetonitrile has a stronger impact on the CO₂ electro-reduction than previously believed.

[1] Griesser, C., et. al., ACS Catalysis 11, 4920-4928 (2021).