[BMIm][PF6]/silicon oil/multi-walled carbon nanotubes paste electrode: Electrochemical properties and application for lead and cadmium ion determinations

The electroanalytical methods have been developed for wide application, especially for trace metal ions. In this study, the applicability of 1-butyl- -3-methylimidazolium hexafluorophosphate ([BMIm][PF6]) ionic liquid as a pasting binder to fabricate a multi-walled carbon nanotube paste electrode (MWCNT PE) for detecting Pb2+ and Cd2+ was evaluated. The electrochemical properties of electrodes were explored by cyclic voltammetry, electrochemical impedance spectroscopy and linear sweep anodic stripping voltammetry. The use of [BMIm][PF6] alone as a conductive binder resulted in an electrode that was unsatisfactory for electrochemical analysis. However, the MWCNT PE with the pasting mixture of silicon oil and [BMIm][PF6] displayed excellent sensitivity for the Pb2+ and Cd2+ determinations, with limits of detection of 2.25 and 1.59 g L-1, respectively. The proposed electrode was demonstrated to be a reliable sensor for accurately quantifying trace amounts of Pb2+ and Cd2+, exhibiting good repeatability, reproducibility and stability.