Electroanalytical thin film electrodes based on a Nafion™ - Multi-walled carbon nanotube composite

A composite film of multi-walled carbon nanotubes (MWNTs) with Nafion™ cation exchanger membrane is prepared by cast deposition on glassy carbon electrodes. The morphologies of the MWNT and MWNT/Nafion™ modified electrode are characterised by atomic force microscopy (AFM). The MWNTs are cylindrically shaped and uniform with a diameter in the range of 40-60 nm. The MWNT/Nafion™ composite film is cast homogeneously onto glassy carbon electrodes.Well-defined voltammetric responses are observed for the Fe(CN)64-/Fe(CN)63- redox system in aqueous 0.1 M KCl. In contrast to electrodes coated only with Nafion™, both anodic and cathodic peak currents depended linearly on the square root of the scan rate over the range of 0.05-0.6 V s ^-1, which suggests diffusion-control and fast electron conduction within the membrane. The anodic stripping response for Cd metal from a solution of 1-4 μM in aqueous 0.1 M acetate buffer solution is demonstrated. The results indicate that the composite electroanalytical film composed of MWNT and Nafion™ is highly sensitive and suitable for potential electrochemical sensor applications.