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. (https://www.nature.com/articles/s41529-019-0087-0)
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. (https://onlinelibrary.wiley.com/doi/full/10.1002/celc.201800750)
N. A. Payne, J. Mauzeroll, Identifying Nanoscale Pinhole Defects in Nitroaryl Layers with Scanning Electrochemical Cell Microscopy, ChemElectroChem 2019, 6, 5439. (https://onlinelibrary.wiley.com/doi/full/10.1002/celc.201901394)
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. (https://www.sciencedirect.com/science/article/pii/S0013468619312861)
We wish you a successful end of the year and a good start into the next one!
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
Battery materials often consist of multi-component composites which are not homogeneous. To study the intrinsic properties of active components is very challenging for conventional electrochemical techniques.
Recently, the Mauzeroll lab investigated single particle aggregates of lithium iron phosphate by scanning micropipette contact method (SMCM). To extend the potential window they used the ionic liquid EMI TFSI. The technique proofed to yield reproducible results and the redox activity of single lithium iron phosphate particles could be measured.
Measuring currents on single particle aggregates down to the lower pA range is no problem for HEKA’s potentiostats and full software implementation makes it very easy to conduct SMCM experiments with ElProScan.
Read the paper: https://onlinelibrary.wiley.com/doi/full/10.1002/celc.201800750
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