Square Wave Voltammetry for Two-Polarized Electrode Electrochemical Detection: A Theoretical-Experimental Study

Two-polarized electrode (2PE) configurations
for electrochemical
sensing allow for reducing costs and simplifying fabrication and miniaturization
of sensors by eliminating the need for a reference electrode, which
can also extend the device’s lifespan and enhance the reproducibility
of its response. From a fundamental perspective, this modification
in the cell design introduces additional considerations, as the counterbalancing
electrochemical reaction at the auxiliary electrode influences the
response and causes deviations from the well-known behavior in conventional
three-electrode setups. In this work, the response of reversible electrode
processes in 2PE systems is studied for one of the most powerful electroanalytical
techniques: square wave voltammetry (SWV). Easy-to-implement mathematical
expressions are derived for the cyclic SWV signal and its components,
as well as for the potential difference and redox surface concentrations
at the two electrode-solution interfaces. The features of the cyclic
SWV signal are analyzed as a function of the key system and technique
parameters to assist the design, use and accurate interpretation of
the cyclic SWV signal in reference electrode-free platforms. Experimental
validation with a standard 2PE cell, as well as with commercial screen-printed
electrodes, is provided.