Oscillations in an array of bistable microelectrodes coupled through a globally conserved quantity.

Area of Science:

• Electrochemistry
• Chemical Engineering
• Physical Chemistry

Background:

• Carbon monoxide (CO) electrooxidation is a bistable reaction with a unique S-shaped negative differential resistance (S-NDR) current-potential curve.
• Coupled microelectrode arrays exhibit complex dynamics due to globally conserved total current.

Purpose of the Study:

• To investigate the dynamical behavior of microelectrode arrays during CO electrooxidation under controlled current.
• To understand the conditions leading to spontaneous potential oscillations in such systems.

Main Methods:

• Experimental investigation of microelectrode arrays under controlled current conditions.
• Mathematical analysis using a two-group approximation to model system dynamics.

Main Results:

• Microelectrodes activate sequentially as total current increases, with one electrode on the intermediate S-NDR branch and others on passive or active branches.
• Spontaneous potential oscillations are observed when a few coupled microelectrodes are activated.
• Mathematical analysis confirms oscillations arise in a minimal model (1 electrode vs. n-1 electrodes, n>=3) when the single electrode is on the intermediate branch and the larger group is active.

Conclusions:

• The coupling in microelectrode arrays during CO electrooxidation can lead to emergent oscillatory behavior.
• A simplified mathematical model accurately predicts the onset of oscillations, highlighting the importance of electrode states within the S-NDR curve.