Prof. Dr. Corina Andronescu
To create a bridge between thermal and electrochemical catalysis, in A02, we will investigate how the presence of O2, known to be a key component in thermal catalysis during electrooxidation of ethylene glycol (EGOR), influences the electrooxidation of EG on Co3O4-derived catalysts. In an initial step, catalyst materials from the C projects, with different cations (Fe, Mn, Ni, V) and anion substitution (N), that are to be evaluated also as heterogeneous catalysts in thermal catalysis, will be explored for EG electrooxidation. The catalysts provided by C projects are embedded in a gas diffusion electrode (GDE) in a three-compartment flow-through electrolyzer, in which O2 will be added from the hydrophobic side of the GDE in a controlled amount using mass flow controllers. Chronopotentiometric measurements will be performed, and product selectivity will be determined in the absence and the presence of different O2 amounts.
The impact of oxygen concentration, hydroxide concentration, electrolyte, current collector, and temperature (up to 80 °C in aqueous-based electrolytes) on the reaction selectivity will be investigated using high-performance liquid chromatography (HPLC). In addition, downstream gas chromatography or differential electrochemical mass spectrometry (DEMS) measurements will be performed to differentiate between oxygen evolution reaction (OER) and EGOR. Correlation between the cation/anion substitution, reaction conditions and selectivity will be derived using tools developed in the INF project. This approach will be further extended to other substrates, such as cinnamyl alcohol, investigated in A01, enabling a comparison between thermal and electrochemical catalysis. A fundamental understanding of how the O2 is impacting the EGOR in the GDE experiments as well as the oxidation state of Co will be done using scanning electrochemical cell microscopy (SECCM) experiments conducted on thin-film Co3O4 on Au or glassy carbon (GC) substrates obtained by electrodeposition or sputtered in A04, B10 or T01. The thin films will have micrometer-sized doped areas done via laser-doping in C05.
Potentiostatic and galvanostatic local measurements will be conducted using SECCM, in a controlled atmosphere with defined O2:Ar ratios around the electrolyte droplet. Catalyst films will be evaluated before and after galvanostatic EGOR experiments. The separation of anodic and cathodic reactions, assumed to take place in thermal catalysis, will be elucidated by SECCM potentiostatic experiments to probe the local anodic and cathodic reactions that may develop on the catalyst surface, including EGOR, oxygen reduction reaction (ORR), as well as Co transformations, such as Co2+ to Co3+. The overlap or anodic current recorded during EGOR, reduction currents recorded during ORR, as well as the study of the oxidation and reduction of the Co-based catalysts, will enable the visualization of the impact of substitution on the measured potentials that may develop at the microscale over the laser-doped thin-films. In addition, the experiments will be complemented by operando studies conducted in A04 and B10, since the same catalyst films will be explored in A02. The local electrochemical experiments will allow correlations with the thermal catalysis experiments.
Figure: (A) SEM image of the catalyst film (the grey spots indicate the regions where the laser treatment using DLIP was applied to induce the Fe modification); (B) The correlation of the current density as well as footprint of the SECCM measure¬ment on the points marked on figures A and C. (C) Current density activity map at 1.75 V vs. RHE. (D) Fluence of the laser at the marked points. (data not published)
A02: High-Resolution Nanoelectrochemical Microscopy and Single Particle Electrocatalysis for Activity-Structure Correlation
Investigation of catalyst particles or catalyst films, which will be cobalt-based spinel and perovskite oxides including Fe, Mn, or V substitution will be performed by scanning electrochemical cell microscopy (SECCM) on thin-film electrocatalyst libraries and laser-treated thin films (C. Andronescu). Sputtered films with libraries of varying elemental composition will be post-annealed to form single crystalline surface areas which will be determined and localized by electron backscatter diffraction (EBSD). SECCM will be performed on these grains to correlate electrochemical activity for the oxygen evolution reaction (OER) as well as ethylene glycol oxidation with the composition and surface structure of the materials. Photoresist-structured catalyst films on TEM grids and SECCM will provide information about the impact of electrocatalysis on the structure and composition of the material. SECCM will be used to study how heteroelements like iron, vanadium or manganese incorporated in thin-film model catalysts (such as Co3O4) after laser treatment.
The particle-on-the-stick approach will be applied to identify the intrinsic activity of defined catalyst particles such as cobalt-based spinel and perovskite oxides with Fe, Mn, or V substitution (W. Schuhmann). Identical location TEM using a specifically designed nanoelectrode-TEM holder provides access to the electrochemically induced structural modifications of the particle during electrocatalysis in accelerated stress tests at extreme current densities. This approach will be further extended to substrate such as cinnamyl alcohol, ethylene glycol, cyclohexene, cyclohexane, and solvent including water, acetonitrile, and dimethylformamide.
Finally, to address the knowledge gap between heterogeneous catalysis and electrocatalysis a continuously operated electrochemical flow-through reactor with temperature control and operated with organic electrolytes will be developed. The catalyst materials will be immobilized on electrodes and electrocatalysis at changing temperatures will be performed. The final step is the transition to a heated high-pressure batch reactor equipped with suitable electrochemical abilities. The dependence of the overpotential and the product variation from the pressure, temperature will be evaluated to correlate results from heterogeneous catalysis and electrocatalysis.
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Last update: Jul 28, 2026
