Carbon Nanotube-Loaded Nafion Film Electrochemical Sensor for Metal Ions: Europium

By Wang, Tingting; Zhao, Daoli; Guo, Xuefei; Correa, Jaime; Riehl, Bill L. & Heineman, William R.
Published in Analytical Chemistry NULL 2014

Abstract

A Nafion film loaded with novel catalyst-free multiwalled carbon nanotubes (MWCNTs) was used to modify a glassy carbon (GC) electrode to detect trace concentrations of metal ions, with europium ion (Eu3+) as a model. The interaction between the sidewalls of MWCNTs and the hydrophobic backbone of Nafion allows the MWCNTs to be dispersed in Nafion, which was then coated as a thin film on the GC electrode surface. The electrochemical response to Eu3+ was found to be ∼10 times improved by MWCNT concentrations between 0.5 and 2 mg/mL, which effectively expanded the electrode surface into the Nafion film and thereby reduced the diffusion distance of Eu3+ to the electrode surface. At low MWCNT concentrations of 0.25 and 0.5 mg/mL, no significant improvement in signal was obtained compared with Nafion alone. Scanning electron microscopy and electrochemical impedance spectroscopy were used to characterize the structure of the MWCNT -Nafion film, followed by electrochemical characterization with Eu3+ via cyclic voltammetry and preconcentration voltammetry. Under the optimized conditions, a linear range of 1 -100 nM with a calculated detection limit of 0.37 nM (signal/noise = 3) was obtained for determination of Eu3+ by Osteryoung square-wave voltammetry after a preconcentration time of 480 s.

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