Preprints
https://doi.org/10.5194/mr-2021-18
https://doi.org/10.5194/mr-2021-18

  15 Feb 2021

15 Feb 2021

Review status: this preprint is currently under review for the journal MR.

An Electrochemical cell for in operando 13C NMR investigations of carbon dioxide/carbonate processes in aqueous solution

Sven Jovanovic1,5, Philipp Schleker1,3, Matthias Streun2, Steffen Merz1, Peter Jakes1, Rüdiger-A. Eichel1,4, and Josef Granwehr1,5 Sven Jovanovic et al.
  • 1Forschungszentrum Jülich, Institute of Energy and Climate Research, Fundamental Electrochemistry (IEK-9), Jülich, Germany
  • 2Forschungszentrum Jülich, Central Institute of Engineering and Analytics, Electronic Systems (ZEA-2), Jülich, Germany
  • 3Department of Heterogeneous Reactions, Max Planck Institute for Chemical Energy Conversion, Mülheim an der Ruhr, Germany
  • 4RWTH Aachen University, Institute of Physical Chemistry, Aachen, Germany
  • 5RWTH Aachen University, Institute of Technical and Macromolecular Chemistry, Aachen, Germany

Abstract. In operando NMR spectroscopy is a method for the online investigation of electrochemical systems and reactions. It allows a real-time observation of the formation of products and intermediates, and it grants insight into the interactions of substrate and catalyst. An in operando NMR setup for the investigation of the electrolytic reduction of CO2 on silver electrodes has been developed. The electrolysis cell consists of a three-electrode setup using a working electrode of pristine silver, a chlorinated silver wire as reference electrode, and a graphite counter electrode. The setup can be adjusted for the use of different electrode materials and fits inside a 5 mm NMR tube, Additionally, a shielding setup was employed to minimize noise caused by interference of external radio frequency (RF) waves with the conductive components of the setup. The electrochemical performance of the in operando electrolysis setup was investigated in comparison to a standard CO2 electrolysis cell. The small cell geometry impedes the release of gaseous products, and thus it is primarily suited for current densities below 1 mA/cm2. The effect of conductive components on 13C NMR experiments was studied using a CO2 saturated solution of aqueous bicarbonate electrolyte. Despite the B0 field distortions caused by the electrodes, line widths of ca. 1 Hz could be achieved. This enables the investigation of interactions in the sub-Hertz range by NMR spectroscopy. It was found that the dynamics of the bicarbonate electrolyte change due to interaction with the electrochemical setup, by catalyzing the exchange reaction between CO2 and HCO3 and affecting the formation of an electrical double layer.

Sven Jovanovic et al.

Status: open (until 20 Mar 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on mr-2021-18', Anonymous Referee #1, 17 Feb 2021 reply
    • AC1: 'Reply on RC1', Sven Jovanovic, 18 Feb 2021 reply
  • RC2: 'Comment on mr-2021-18', Anonymous Referee #1, 17 Feb 2021 reply
    • AC2: 'Reply on RC2', Sven Jovanovic, 18 Feb 2021 reply

Sven Jovanovic et al.

Sven Jovanovic et al.

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Short summary
This work presents a setup for the investigation of electrochemical processes during operation (in operando) using nuclear magnetic resonance (NMR) spectroscopy. The setup was designed to minimize the interferences between the NMR instrument and the electrochemical equipment. Employing this setup, the dynamic equilibrium of carbon dioxide in aqueous bicarbonate electrolyte has been monitored in operando, revealing that it may be affected by the electrochemical equipment itself.