Improving the stability of Pb2+ ion-selective electrodes by using 3D polyaniline nanowire arrays as the inner solid-contact transducer

Abstract

Polyaniline nanowire arrays (PANI- NWA) were synthesized by electrochemical deposition, then successfully applied as the ion-to-electron transducer in ion selective electrodes (ISEs) for the detection of aqueous Pb2+ ions. When used as the solid-contact layer in Pb2+-ISEs, the PANI- NWA delivered a high capacitance and low impedance as measured by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively, thus delivering efficient ion-to-electron transfer. Owing to the open structure of the nanowire arrays, Pb2+ ions can able to easily penetrate the PANI layer, further enhancing the detection efficiency. Developed GC/PANI- NWA/Pb2+-ISE showed outstanding potentiometric performance, including a low Pb2+ detection limit (2.5 × 10−8 M), a short response time (about 1 s), high stability in N2 (or O2) and no light sensitivity. Further, the water layer between the solid-contact layer and the ISM was largely eliminated when three-dimensional PANI- NWA were applied as the solid contact layer, thus enhancing the stability of the ISE.