The Effects of Thin Layer Diffusion at Glassy Carbon Electrodes Modified with Porous Films of Single-Walled Carbon Nanotubes

Due to their small size and remarkable electrical properties, carbon nanotubes have been used to modify electrode surfaces to create sensors for a range of important analytes. In this study, glassy carbon (GC) electrodes modified with films of HiPCo ® single-walled carbon nanotubes (SWCNTs) were prepared by drop-coating dispersions of the nanotubes. A number of different solvents were evaluated for this purpose. Atomic force microscopy was used to show the porous nature of the nanotube assemblies. The modified electrodes were used in the determination of dopamine and epinephrine, and compelling evidence of thin-layer mass transport regimes within the porous films was observed using cyclic voltammetry. The work described here exposes some potentially flawed arguments commonly made in the literature regarding the ‘catalytic’ properties of nanotubes. We believe that the issues raised must be addressed if the much-promised applications of nanotubes in sensor devices are to become a reality.