Quantitative aspects of ohmic microscopy.

Area of Science:

• Electrochemistry
• Surface Science
• Analytical Chemistry

Background:

• Cyclic voltammetry is a common electrochemical technique.
• Understanding potential distribution is crucial for electrode analysis.
• Non-uniform electrode surfaces present challenges in electrochemical measurements.

Purpose of the Study:

• To investigate the potential difference (Δφ(sol)) in an electrochemical cell during cyclic voltammetry.
• To compare experimental Δφ(sol) measurements with theoretical predictions.
• To establish a foundation for ohmic microscopy as a quantitative imaging tool.

Main Methods:

• Conventional cyclic voltammetry experiments were conducted using a platinum disk electrode.
• The setup involved an axisymmetric cell configuration with microreference electrodes.
• Potential differences (Δφ(sol)) were measured across the electrolyte solution.

Main Results:

• The measured Δφ(sol) vs. applied potential (E) curves closely resembled standard voltammograms.
• The position of the microreference probes did not significantly affect the observed Δφ(sol) curves.
• Experimental Δφ(sol) values showed strong agreement with predictions from primary current distribution theory (Newman's formalism).

Conclusions:

• The study validates the use of potential difference measurements in electrochemical cells.
• The findings support the theoretical framework for understanding current distribution on electrodes.
• This work provides a basis for developing ohmic microscopy for spatially resolved imaging of heterogeneous electrode surfaces.