Nanogap electrodes as a tool for exploring overlapping electrochemical double-layer regions and their application in electrochemical sensors

• Applicant: Dr. Jochen Kieninger
• Subject Area: Measurement Systems ; Microsystems
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 547363313

The electrochemical double layer at the interface from the electrolyte to the electrode plays a central role in almost all electrochemical applications, for example, in sensor technology or energy conversion. At the same time, our knowledge is based on traditional measurements with mercury electrodes and modern interpretations based on modeling, without being able to underpin this comprehensively with adequate electrochemical measurement technology. In this project, we realize nanogap electrodes in a technologically challenging arrangement as parallel plate capacitors with adjustable distances in the range of 10-50 nm and use these structures for electrochemical measurements in the domain between just touching and overlapping double-layer areas. The key to creating the nanogap is a sacrificial layer of copper, where the thickness can be adjusted by the number of cycles monolayer by monolayer in an electrochemical atomic layer deposition. These electrodes give us direct metrological access to borderline cases in which the classic double-layer models can be brought to contradiction. We expect this project will enable us to close the gap between traditional electrochemical measurement technology and situations in the electrochemical double layer that have only been described by models. At the same time, the tools developed can be used as electrochemical sensors, especially for measurements in weakly conductive electrolytes.

• DFG Programme: Research Grants