Measuring the impact on impedance spectroscopy of pseudo-reference electrode accumulations

Silver is widely used on screen-printed electrodes (SPEs) to provide a reference potential for electrochemical measurements such as impedance spectroscopy (EIS). The redox activity between silver and electrolyte in SPE-based experiments is rarely reported in detail, despite the critical reliance of potentiometric measurement accuracy on the predictability of reactions at reference electrodes. In this work, potassium ferrous cyanides typically used as electrolyte components were shown to adsorb to the silver surface when applied to SPEs. EIS was performed in a two-electrode configuration to demonstrate redox instability at the silver electrode, highlighting the need for evaluation of similar systems to prevent reference potential drift caused by side reaction depositions.