Electrochemical Characterization of and Stripping Voltammetry at Screen Printed Electrodes Modified with Different Brands of Multiwall Carbon Nanotubes and Bismuth Films

Abstract

A screen-printed electrode sensor has been fabricated by modifying the carbon ink surface with different brands of multiwall carbon nanotubes (MWCNTs) and bismuth film (BiF) for the determination of traces of lead, cadmium and zinc ions by square wave anodic stripping voltammetry. The MWCNTs, from three different sources, were functionalized and dispersed in Nafion (MWCNT-Nafion) solution and placed on screen printed electrodes (MWCNT-Nafion/SPE); bismuth films were then prepared by ex-situ plating of bismuth onto the MWCNT-Nafion/SPE electrodes. The electrochemical characteristics of BiF/MWCNT-Nafion/SPE/ were examined by electrochemical impedance spectroscopy and showed differences; the charge transfer resistance tends to decrease with negative applied potentials. After optimizing the experimental conditions, the square-wave peak current signal is linear in the nmol L−1 range. The lowest limit of detection found for the separate determination of lead, cadmium and zinc were 0.7 nmol L−1, 1.5 nmol L−1, and 11.1 nmol L−1, respectively, with a 120 s deposition time.