Kinetics Study Of Cd2+ Ions In Sodium Sulfate Solution at Carbon Nanotube Electrode

The electrochemical response to Cd2+ ions on an electrode of carbon nanotubes functionalized with carboxylic acid group was studied mainly by use of cyclic voltammetry in aqueous sodium sulfate. A well-defined quasi-reversible voltammograms for the Cd2+/Cd redox couple were shown on the carbon nanotube electrode, and the anodic and cathodic peak potentials were -0.67 V and -0.92 V vs. SCE at a scan rate of 50 mVs-1, respectively. Both anodic and cathodic peak currents depended linearly on the square root of the scan rate over the range of 0.05-0.8 Vs-1. Such linearity indicated that the reaction rate was limited by semi-infinite linear diffusion of the analyte to the interfacial reaction zone. The electron-transfer and diffusion coefficients for Cd2+/Cd were evaluated from the dependence of the voltammograms on the potential scan rate and concentration of analyte.