SECM

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 HCOO– and 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). https://doi.org/10.1038/s42004-020-00399-6.

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). https://doi.org/10.1038/s42004-020-00399-6.

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). https://doi.org/10.1038/s42004-020-00399-6

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

By Mareike Haensch, ago

Remote SECM Mini Workshop

We had a great remote mini workshop with Martin Edwards from the University of Arkansas and Hang Ren from Miami University in Ohio and their students from scanning probe microscopy and electroanalytical techniques courses.
Our application scientist Mareike Haensch performed SECM experiments on the ElProScan starting from mounting the sample and microelectrode to recording images in different SECM modes. The students actively participated and suggested changes of parameters to see how it influences the experiment. We hope that this remote “hands-on” experience helps deepen their understanding of SECM in times during which lab courses are not possible in many places around the world.

By Mareike Haensch, ago

SECM Tutorial at the ISE Online Meeting

This year Prof. Gunther Wittstock from Oldenburg and Prof. Wolfgang Schuhmann from Bochum, two true experts in the field of scanning electrochemistry microscopy (SECM) will hold an online tutorial at the ISE annual meeting with the title

“Solving research problems by means of scanning electrochemical microscopy (SECM) and related techniques”

The online meeting will consist of online lectures, poster sessions and tutorials.

ISE logo

31st August – 4th September

(The exact time of the tutorial is not yet fixed)

Deadline for registration is 31st of July.

The registration for ISE members is FREE and for non-members it cost 50€ above 30 years and 15€ below 30 years.

Register to take this opportunity and learn everything about SECM that you always wanted to know!

By Mareike Haensch, ago

Influence of mechanical microenvironment on the redox state of cardiomyocytes

The regulation of intracellular redox microenvironment is of immense importance for the homeostasis of cells. The mechanical microenvironment plays a key role in the regulation of the phenotype and function of cardiac cells, which are strongly associated with the intracellular redox mechanism of cardiomyocytes. Glutathione (GSH) is the most abundant intracellular nonprotein thiol and functions as one of the most important endogenous antioxidants in cells. Under normal physiological conditions, intracellular chemical microenvironment is maintained in a relatively reduced state due to a higher GSH concentration than that of glutathione disulfide (GSSG). the relationship between the redox state of cardiomyocytes and their mechanical microenvironment remains elusive.

The Li Lab at the BEBC at Xi’an Jiaotong University investigated the influence of the mechanical microenvironment on the redox state of single cardiomyocytes in situ by SECM. The redox state was studied by quantifying the GSH level of living cardiomyocytes at single-cell level. Different mechanical microenvironments were simulated using polyacrylamide (PA) gels of different stiffness as the substrate. SECM depth scans were recorded and aprroach curves extracted to obtain rate constants kf for the reaction of the redox mediator FcCOOH and GSH which are a direct measure of GSH levels.

Li, Y., Lang, J., Ye, Z., Wang, M., Yang, Y., Guo, X., Zhuang, J., Zhang, J., Xu, F. and Li, F. (2020) ‘Effect of Substrate Stiffness on Redox State of Single Cardiomyocyte: A Scanning Electrochemical Microscopy Study’, Analytical Chemistry.

It was shown that stiffer substrates induce a more oxidative state of the cardiomyocytes compared to the softer substrates. This result can contribute to understand the effect of mechanical factors on the cell’s redox mechanism, such as the myocardial fibrosis caused overaccumulation of ECM.

SECM proved to be a sensitive, label-free and in situ technique for the investigation of redox state in single-cells.

HEKA’s ElProScan ELP 3 provides the ideal conditions for working with live single cells. The inverted microscope allows visual control of the cells and exact positioning of the microelectrode and a range of heated stages for working under physiological conditions. The unique depth scan allows the study of concentration profiles above single cells.

By Mareike Haensch, ago

Study of antimicrobial coatings by SECM

The infection of implants poses a common problem. It has been shown that photoactive titanium dioxide coatings can prevent microbial infections by producing free radicals under illumination. Because these free radicals can also damage adjacent cells, it has to ensured that their existence is confined to the implant surface.

The Sant Lab characterized a nitrogen- and self-doped titania coating which produces free hydroxyl radicals upon illumination of the material. Among other characterization techniques the coating was investigated by SECM towards the effects of free radicals on a reducible and oxidizable redox mediator upon irridation in different distances from the coating surface. It could be shown that the existence of free radicals is indeed confined to the vicinity of the surface.

The ElProScan in combination with our acquisition and analysis software POTMASTER allows the creation of complex protocols for automated experiments. The online analysis can display distance-dependent values, e.g. peak currents from a CV while you are still measuring.

Read the paper: https://pubs.acs.org/doi/10.1021/acsomega.9b02188

By Mareike Haensch, ago

Study Corrosion Processes Locally with SECM and SMCM

The Mauzeroll Lab shows how to gain a deeper understanding of corrosion processes of thermal spray coatings by combining macro electrochemical techniques with localized measurements by scanning electrochemical microscopy (SECM) and scanning micropipette contact method (SMCM).

HEKA’s ElProScan fully supports SMCM, a technique where a miniaturized electrochemical cell is formed with a droplet at the tip of a nano- or micropipette. The wetted sample surface functions as working electrode and a Ag/AgCl wire inside the pipette functions as quasi reference/counter electrode. This method provides a unique way for localized measurements, which helped Janine and her group to probe corrosion processes very locally and record Tafel plots at the micron-scale!

HEKA’s Ultra Potentiostats (PG 611 and 618 USB) are the ideal instruments for measuring low currents due to their low noise performance and high current resolution! This allows such challenging localized corrosion studies within these tiny electrochemical cells formed by the droplet.

Have a look at the paper: https://www.nature.com/articles/s41529-019-0087-0

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By Mareike Haensch, ago