Behind the Science: When a Nanoparticle Hits an Electrode

Dr. Kate Lawrence, Editor of ChemElectroChem, talked to Professor Kristina Tschulik, Ruhr University Bochum, Germany, about her recent article on nano impact experiments.

Nano impact electrochemistry is used to measure a transient signal while a nanoparticle hits an electrode due to its motion in a solution. A variety of information can be obtained from this current pulse, yet its accurate measurement is challenging due to its short duration and small amplitude. Tschulik and her colleagues have developed a general guideline to researchers for accurate electrochemical nano impact measurements.

What was the inspiration behind this study?

Nano impact experiments provide new possibilities for chemists to understand electrochemistry down to the nanoscale level. However, they come with many challenging aspects. Whilst experimentalists are trying to extract a maximum of possible information, the potentiostats they use may not be designed to measure this type of transient signals at a low current range.

At first, we were very surprised that even the high-bandwidth instrument we have used, which is more than sufficient for conventional electrochemistry measurements, still distorted our nano impact data significantly. This motivated us to take a closer look at the effects of the setup used in nano impact studies on the measured data.

What did you find?

Unlike conventional measurements, the nano impact data can be significantly modified even by state-of-the-art measuring instruments. Understanding these effects is important before interpreting and analyzing the data. Unfortunately, the commercial potentiostats are proprietary and information about the design and technical specifications are not fully accessible. This makes it difficult to evaluate the experimental setup based on this limited information.

Additionally, each setup can be different and the evaluation of results from one system is not necessarily applicable to another. This is why we provided both testing results from certain devices and a simple and reproducible method which electrochemists can use to test the response of their own setup. With the examples and the method, we have provided in the paper, electrochemists have a guideline to validate their own experimental setup and acquire reliable nano impact results, especially if information about the peak height and peak duration are the point of interest.

Why was your attention focused on this particular area?

Nano impact is an emerging field of electrochemistry which is constantly growing. The technique can be applied to various electrochemical systems in order to obtain a wide range of information. Based on measuring a charge, the nanoparticles’ size distribution, their composition and/or aggregation can be received [1–5].

We and several others are also improving this method and looking for new possibilities, such as studying the mechanistic and catalytic properties of nanomaterials [6–8]. These additional applications are promising, yet require more information to be extracted from the signals, such as the peak duration and peak height of the current signals. These additional parameters need to be carefully validated as they are more sensitive than the electric charge.

What is the broader impact of this paper for the scientific community?

In general, we have provided a simple yet powerful tool to generate well-defined current signals. It can be used to evaluate not only the nano impact experimental setup, but any potentiostat response to investigate its capability and limitation for the electrochemical measurements.

We hope that electrochemists who intend to study nano impact electrochemistry can use this work as a starting point to obtain accurate measurements and exciting new results. In a broader sense, the work emphasizes the importance of evaluating experimental setups, given the fact that measurements using a ‘black box’ may lead to avoidable misinterpretations of the extracted data.

The article they talked about