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Updated: Oct 6, 2025
10:28
Probing the Structure and Dynamics of Interfacial Water with Scanning Tunneling Microscopy and Spectroscopy
Published on: May 27, 2018
8.9K
Double-layer structure of the Pt(111)-aqueous electrolyte interface
Kasinath Ojha1, Katharina Doblhoff-Dier1, Marc T M Koper2
1Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands.
Summary
We measured the double-layer capacitance at the platinum-electrolyte interface, finding deviations from standard models at low concentrations. Ion size and hydration influence capacitance at higher concentrations, leading to a new interface model.
Area of Science:
- Electrochemistry
- Surface Science
- Physical Chemistry
Background:
- The electrical double layer at electrode-electrolyte interfaces is crucial for electrochemical processes.
- Traditional Gouy-Chapman-Stern (GCS) theory describes this layer but has limitations.
- Understanding the Pt(111)-electrolyte interface is key for catalysis and sensing.
Purpose of the Study:
- To investigate the double-layer capacitance of the Pt(111)-electrolyte interface near the potential of zero charge (PZC).
- To identify deviations from GCS theory and explore ion-specific effects.
- To develop an improved model for the electrical double layer structure.
Main Methods:
- Detailed capacitance measurements of the Pt(111)-electrolyte interface.
- Systematic variation of electrolyte concentrations and ion types.
- Formulation of a new double-layer model by combining existing theories.
Main Results:
- Observed significant deviations from GCS behavior at low electrolyte concentrations, independent of ion type.
- Identified ion-specific capacitance effects related to ion size and hydration at higher concentrations.
- Developed a model that accurately reproduces experimental capacitance data.
Conclusions:
- The Pt(111)-electrolyte interface exhibits complex behavior beyond GCS theory.
- Ion-surface interactions and water reorganization significantly influence the double layer structure.
- The new model provides a more comprehensive understanding of interfacial phenomena.
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