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.