Screening of CO2 electroreduction catalysts

The electroreduction of carbon dioxide is an important reaction in view of fuels for both fuel cells and redox flow batteries as well as towards a carbon neutral energy cycle. Hence the reaction has been intensively studied and a range of different catalyst materials have been presented.

In today’s paper “Scanning electrochemical microscopy screening of CO2 electroreduction activities and product selectivities of catalyst arrays” by Francis D. Mayer et al. Sn/SnOx catalysts are investigated using SECM. The final goal of this approach is to obtain a high-throughput screening procedure with the ability of spatial resolution to evaluate local activity changes in the catalysts.

Here, the authors show the capability of SECM for CO2 electroreduction catalyst screenings by comparing three different Sn/SnOx materials towards the production of H2, COad and HCOOand their selectivity. In contrast to traditional SECM experiments where the microelectrode is biased at a constant potenial while moving across the surface, the products are detected in a CV cycle as shown below. This allows for a simultaneous detection of all three relevant reaction products in one experiment.

Presentation of A CV at a Pt microelectrode for the simultaneous detection of H2, COad and HCOO-.
Fig. 1: Cyclic voltammograms indicating the different redox processes during CO2 electroreduction. Image taken from Mayer, F.D., et al. Commun Chem 3, 155 (2020).

The screening of the Sn/SnOx catalyst array was performed by conducting and analysing a fast CV (1 V/s) at the Pt microelectrode at each measuring point of the 8750 x 1250 µm map. The Potmaster software of the ElProScan allows to perform matrix scans where advanced protocols can be executed and analyzed which made these experiments possible.

SECM maps created from the analysis of fast CV scans at each point of the map.
Fig. 2: Resulting maps of the catalyst array for each product as analyzed in the CV scans. Image taken from Mayer, F.D., et al. Commun Chem 3, 155 (2020).

The analysis showed indeed differences in the product selectivities and shows the great potential of using the combined SECM-CV approach for larger catalyst arrays.

Read the full paper here: Mayer, F.D., Hosseini-Benhangi, P., Sánchez-Sánchez, C.M. et al. Scanning electrochemical microscopy screening of CO2 electroreduction activities and product selectivities of catalyst arrays. Commun Chem 3, 155 (2020).

Contact us if this application caught your attention and you want to learn more.

Micropatterning of a photocatalyst surface followed by evaluation of its local catalytic activity

The ElProScan ELP 3 SPECM has been used for an innovative two-step scanning photoelectrochemical microscopy (SPECM) experiment consisting of micropattering and consecutive evaluation of catalytic activty.

In the first step, a BiVO4 seminconductor surface was modified by photodeposition with the electrocatalyst FeOOH to fabricate a photocatalyst system for the photoelectrochemical water splitting reaction. The inverted microscope of the ELP 3 was hereby used to illuminate different spots of the surface with varying illumination time (10, 15, 20 and 25 min) in a matrix scan. This way, a regular pattern with catalytically active spots with different loadings of FeOOH were produced.

In the second step, the photocatalyst pattern was scanned via SPECM and the photocurrent at the sample was recorded yielding a map showing that the highest catalytic activity is found for the spot after 20 min of photodeposition. Additionally, to determine the Faradayic efficiency the oxygen which was produced in the water splitting reaction was detected by the oxygen reduction reaction (ORR) at a microelectrode . The microelectrode was aligned with inverse microscope and therefore with the illuminated sample area. Shear Force Sensing was used to keep a constant distance between microelectrode and sample surface to probe the pure catalytic activity without effects of sample topography. The z position of the microelectrode is further used to obtain the topography map of the sample.

Photodeposition of FeOOH catalyst spots with different loading on a BiVO4 semiconductor surface by SPECM (left) and consecutive evaluation of their catalytic activity by SPECM (right). The recorded signals are the photocurrent at the sample, the locally produced oxygen at the microelectrode and the topography via Shear Force Sensing.

Chen, S., Prins, S. and Chen, A. (2020) ‘Patterning of BiVO4 Surfaces and Monitoring of Localized Catalytic Activity using Scanning Photoelectrochemical Microscopy’, ACS Applied Materials & Interfaces.

These experiments show that the multi-functional ELP 3 SPECM can be used to easily fabricate catalyst libraries which can in a second step be evaluated regarding their local catalytic activity greatly accelerating the search for new highly active catalyst materials.

The latest model of our ELP 3 SPECM-FL has a second illumination port for small spot illumination for illuminated spot sizes down to 5 µm. This match of illuminated sample area and microelectrode size further improves the collection efficiency at the microelectrode and the quality of the experimental results.

Holiday reading

While spending some time outside the lab to recover and enjoy the holiday season, why not have some reading material at hand?

We collected some recent articles on scanning micropipette techniques which are gaining increasing popularity at the moment.

With scanning micropipette techniques, the local electrochemistry of your sample can be studied. A micropipette is filled with electrolyte to form a small droplet at the opening. This droplet is brought into contact with the sample and forms a miniaturized electrochemical cell. This way, common bulk electrochemical experiments can be performed on the micron scale with spatial resolution. Polpular applications are the study of corrosion, coatings, battery materials and (photo)catalysts.

These scanning techniques are commonly called either scanning electrochemical cell microscopy (SECCM) or scanning micropipette contact method (SMCM) and might employ either double-barrel or single barrel micropipettes. If the micropipette is not scanned in a regular pattern, but rather moved to specific spots to collect local data, the technique is also just called micropipette contact method.

Gateman, S.M., Halimi, I., Costa Nascimento, A.R. et al., Using macro and micro electrochemical methods to understand the corrosion behavior of stainless steel thermal spray coatings. npj Mater Degrad 2019, 3, 25. (

M. Dayeh, M. R. Z. Ghavidel, J. Mauzeroll, S. B. Schougaard, Micropipette Contact Method to Investigate High‐Energy Cathode Materials by using an Ionic Liquid, ChemElectroChem 2019, 6, 195. (

N. A. Payne, J. Mauzeroll, Identifying Nanoscale Pinhole Defects in Nitroaryl Layers with Scanning Electrochemical Cell Microscopy, ChemElectroChem 2019, 6, 5439. (

Beugré, R.; Dorval, A.; Lizotte Lavallée, L.; Jafari, M.; Byers, J.C., Local electrochemistry of nickel (oxy)hydroxide material gradients prepared using bipolar electrodeposition, Electrochimica Acta 2019, 319, 331-338. (

We wish you a successful end of the year and a good start into the next one!