Cu@Pd Core–Shell Nanostructures on Pencil Graphite Substrates as Disposable Electrochemical Sensors for the Detection of Biological Amines

Adsorption of molecules at the electrode/solution interface is of great significance in understanding heterogeneous electron transfer processes. Herein, we study the interfacial properties of copper–palladium core–shell nanostructures in a phosphate buffer solution under two different conditions. At low potentials, we show that selective interaction with dopamine over ascorbic acid and uric acid enabled selective analysis of dopamine. At high applied potentials, oxygen evolution reactions were inhibited by the adsorption of histamine at the interface. The adsorption was demonstrated to be influenced by the concentration, enabling the highly sensitive detection of histamine by the electrochemical impedimetric method. Both analytes exhibited excellent sensitivity with linear ranges at low concentrations. Using this strategy, dopamine could be estimated in a linear range of 100 nM to 3 mM with a limit of detection as low as 12 nM while histamine provided a linear range from 1 pM to 1 μM. These insights of adsorption of the analytes at the interface provide an opportunity for the fabrication of advanced sensor development and achieving unexplored horizons of interfacial electrochemistry.