Solid-contact ion-selective electrodes based on ferrocene-functionalized multi-walled carbon nanotubes

Abstract Solid contact materials based on hydrophobic conductors with a large surface area and high double-layer capacitance (e.g. nanostructured materials) have been reported to provide excellent potential stability to ionophore-based solid-contact ion-selective electrodes (SCISEs). In this respect various carbon materials have emerged as versatile and cost-effective solid contact materials. However, it is generally difficult to control and reproduce the standard potential of ISEs with such capacitive solid contacts. Here we introduce ferrocene-functionalized multi-walled carbon nanotubes to provide redox properties to purely capacitive solid contacts as a means of further controlling the standard potential of the corresponding SCISEs.