Insight into the electrochemical performance of heavy metal-free quantum dots in different buffered ferricyanide/ferrocyanide redox systems

The ferricyanide/ferrocyanide K3[Fe(CN)6]/K4[Fe(CN)6] redox couple is a widely utilized redox probe in electrochemistry. Buffering the K3[Fe(CN)6]/K4[Fe(CN)6] system has become one of the ways to generate improved electron transfer rates and stable electrochemical systems. In recent years, semiconductor quantum dots (QDs) have gained popularity as nanotags in electrochemical applications. Herein, we report on the comparative electrochemical behaviour of cadmium-free AuZnFeSeS quantum dots (QDs)-modified screen-printed carbon electrode (SPCE) in different buffered K3[Fe(CN)6]/K4[Fe(CN)6] electrolyte solutions using voltammetry and electrochemical impedance spectroscopy (EIS) techniques. Our results showed that the QDs/SPCE exhibited faster electron transfer rates, lower energy barrier and lower charge transfer resistance (Rct) in the studied buffered electrolyte solution.