Comparison of multi-walled carbon nanotubes and poly(3-octylthiophene) as ion-to-electron transducers in all-solid-state potassium ion-selective electrodes

Multi-walled carbon nanotubes (MWCNTs) were compared with poly(3-octylthiophene) (POT) as ion-to-electron transducer in all-solid-state potassium ion-selective electrodes with valinomycin-based ion-selective membranes. MWCNTs and POT were mixed with the other components of the potassium ion-selective membrane cocktail (valinomycin, KTpClPB, o-NPOE, PVC, THF) which was then applied on a glassy carbon (GC) substrate to prepare single-piece ion-selective electrodes (SPISEs). Results from potentiometric and impedance measurements showed that the MWCNT-based electrodes have a more reproducuible standard potential and a lower overall impedance than the electrodes based on POT. Both types of electrodes showed similar sensitivity to potassium ions and no redox sensitivity.