The effect of ultraviolet photocatalytic oxidation on ferrocyanide electrochemical behavior—An important factor in mediator-based electrochemical sensors

The ferrocyanide/ferricyanide (‘fcn’) ion is a redox-coupled molecule used frequently as an analysis and validation analyte in electrochemical and optical measurements, due to its stability and reversibility features. However, currently there are no studies of how fcn's electrochemical properties are affected by irradiation photocatalysis. In this work we present, for the first time, a shift in the electrochemical properties of a fcn couple by executing a continuous cyclic voltammetry test under the influence of multiple irradiation wavelengths (UV, blue, yellow, and brightfield). UV wavelength irradiation led to a significant shift in the half-wave potential (E_half), converging to a new steady state. We suggested a thermodynamic model including ferrocyanide, ferricyanide, and an electrochemically non-active pentacyanoaquaferrate to describe the change in electrochemical behavior. Enriching one's knowledge of a fcn electrochemical response to irradiation photocatalysis is crucial for electrochemical-optical experiments and may suggest its use for a stable UV detection test.