Single-piece solid-contact ion-selective electrodes with polymer–carbon nanotube composites

Single-piece all-solid-state ion-selective electrode was fabricated with polymer–carbon nanotube composites. The ion-sensing cocktail containing plasticizer, poly(vinyl chloride) (PVC) and multi-wall carbon nanotube (MWCNTs) in polymeric dispersant is drop cast directly on a solid substrate to form the electrode. Polymeric dispersants with MWCNTs showed good compatibility in plasticized PVC matrix. The introduction of 0.2–0.5 wt% carbon nanotubes as ion-to-electron transducer has much improved the potential stability of the solid-contact electrode. It also makes an essential role to enhance the hydrophobicity of the membrane, which contributes to the more stable potential signal by elimination of undesirable water layer at the interface. The single-piece solid-state sensors with different ionophores were easily fabricated. Such electrodes exhibited excellent sensing properties comparable to the corresponding liquid-contact electrodes.