Dispersion studies of carboxyl, amine and thiol-functionalized carbon nanotubes for improving the electrochemical behavior of screen printed electrodes

Carbon nanotubes (CNTs) are nanostructures that have been discovered in 1991 but their interest continues growing due to their excellent properties and possible applications. In the field of Electroanalysis, most of those are based on the modification of working electrodes using solutions or dispersions in suitable solvents. However, the dispersing agent could have an important effect on the electrochemical behavior of analytes. In this work, an exhaustive study of dispersion of multi-walled carbon nanotubes (MWCNTs) functionalized with carboxylic (COOH), thiol (SH) and amine (NH2) groups in various solvents is performed. The electrochemical characterization of gold screen-printed electrodes (Au-SPEs) nanostructured with these dispersions of CNTs is carried out by recording the electrochemical signal from the redox reactions of a model analyte, methylene blue, by different electrochemical techniques (CV, SWV and DPV). Evaluation of the influence of the dispersing agent by itself is also made.