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Nanoscale Mapping of the Double Layer Potential at the Graphene-Electrolyte Interface
Evgheni Strelcov1,2, Christopher Arble1, Hongxuan Guo3
1Physical Measurement Laboratory , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States.
Nano Letters
|January 29, 2020
Summary
Researchers developed a new method to measure the electrical double layer (EDL) potential drop in high-concentration electrolytes using graphene-capped cells and Kelvin probe force microscopy (KPFM). This technique offers high spatial resolution for studying electrochemical interfaces.
Area of Science:
- Electrochemistry
- Surface Science
- Nanotechnology
Background:
- The electrical double layer (EDL) is crucial for electrochemical devices and biological processes.
- Existing EDL probing methods lack spatial resolution.
- Traditional Kelvin probe force microscopy (KPFM) is limited to low electrolyte concentrations (< several mmol/L).
Purpose of the Study:
- To overcome the concentration limitations of KPFM for EDL measurements.
- To develop a high-resolution method for probing EDL potential drops in concentrated electrolytes.
- To enable in operando and in vivo studies of electrochemical interfaces.
Main Methods:
- Combining KPFM with novel graphene-capped electrolytic cells.
- Quantitative measurement of potential drop across the EDL in aqueous electrolytes (0.1 mol/L to molar concentrations).
- Utilizing numerical modeling to understand graphene's role in potential screening and EDL determination.
Main Results:
- Successfully measured EDL potential drops at high electrolyte concentrations (decimolar and molar) with nanoscale lateral resolution.
- Demonstrated the capability to image spatially inhomogeneous systems, such as nanoparticles in solution.
- Reported surface potential measurements of graphene in contact with various electrolyte solutions.
Conclusions:
- The developed KPFM-based approach overcomes previous concentration limitations for EDL measurements.
- This method provides high-resolution insights into EDL phenomena in concentrated electrolytes.
- The technique is suitable for studying nanocatalysts, biological cells, and other inhomogeneous systems in liquid environments.
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