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Reedijk Symposium 2022: Process development for electrochemical reduction of CO2

Friday 28 October 2022
Gorlaeus Lecture Hall Building (collegezalengebouw), Einsteinweg 57
Lecture Hall 1


Electrochemical reduction of CO2 to value added products is highly desirable to establish a sustainable chemical industry. In this presentation I will discuss the latest developments on the design and operation of electrochemical cells based on Gas Diffusion electrodes based on Cu, Ag, or Au, including the preparation, mode of operation (flow through, flow-by), and the origin of a phenomenon called ‘flooding’ – causing deterioration of the cell performance. Using a cell design i) containing a Sustainion membrane, ii) allowing a liquid flow of catholyte and anolyte, and iii) providing convective supply of CO2, outstanding faradaic efficiencies towards carbon monoxide (FECO = 85%, at -0.88 V vs RHE and 50 mA.cm-2) were obtained.  Most importantly, in this configuration, cell performance could be maintained for at least 10 hours of continuous operation.

Also the anode composition will be discussed to be important in determining the stability of the cell. We will demonstrate Ni anodes are unfavorable, due to cross-over of Ni from anode to cathode, resulting in excessive formation of hydrogen.

Finally, special attention will also be given to the electrolyte composition, including the use of acetonitrile with imidazolium additives. Imidazolium cations in acetonitrile lead to unprecedently low overpotentials for CO2 reduction on Au, with ~ 100% Faradaic efficiency to CO. By modification of the N1 and N3 functionality of the imidazolium cation, we show a direct correlation between the performance in CO2 reduction and the C2-H acidity of the cation. The demonstrated mechanism provides guidelines for improvement in the energy efficiency of non-aqueous electrochemical CO2 reduction, by a tailored design of electrolyte cations.


After obtaining a MSc in chemistry, with a specialization in heterogeneous catalysis from the University of Utrecht in 1992, Guido received his PhD in 1997 from the Delft University of Technology on a thesis on catalytic purification of Diesel exhaust gas. After a Post-Doc position at SRI-International (Stanford Research Institute) (1997-1999), he was awarded a fellowship of the KNAW (Royal Netherlands Academy of Arts and Sciences) to return to the Delft University of Technology as assistant professor, investigating the mechanism of heterogeneous catalytic processes using in situ spectroscopy and transient kinetics. He was awarded a VIDI scholarship in 2005 to develop liquid phase (photo)catalytic processes. 

In 2009 he was appointed full professor initiating the research group ‘Photocatalytic Synthesis’ at the University of Twente. Prof. Dr. Guido Mul is a leading scientist in synthesis and performance evaluation of (photo)electrodes and photocatalysts for environmental and industrial applications, and published over 200 peer-reviewed papers. He chairs the discipline of chemical engineering at the UT, is a member of the Dutch ECCM advisory committee (Electrochemical Conversion and Materials), a member of the CCPTS council (Chemical Conversion, Process Technology, and Synthesis (Top Sector Chemistry)), editorial board member of the international journals “ChemElectroChem“ and “ACS Environmental Science & Technology – Engineering”, and presently cooperates with industry in various Public-Private, and Dutch Science Foundation-funded consortia. Finally he enjoys teaching the courses Process Engineering, Industrial Chemistry and Processes, Advanced Catalysis, and Electrochemical Engineering.

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