A comparative study of carbon nanotube dispersions assisted by cationic reagents as electrode modifiers: Preparation, characterization and electrochemical performance for gallic acid detection

In this work, we report on the preparation of electrodes modified with carbon nanotubes (CNT) films, which provide improved electroanalytical performance towards the polyphenol gallic acid. These films were obtained from aqueous dispersions of the unmodified nanomaterial by the drop-casting method. Cationic reagents such as polyethylenimine (PEI), poly(diallyldimethylammonium chloride) (PDDA) or cetyltrimethylammonium chloride (CTAC) were employed to assist in the dispersion process of carbon nanotubes by ultrasonic treatment. A critical analysis of the influence of the experimental conditions set for the preparation of such dispersions on the electrochemical performance of the modified electrodes has been carried out. The voltammetric experiments have demonstrated that films produced from PEI/CNT and CTAC/CTN dispersions prepared under optimized conditions showed excellent electrochemical performance for gallic acid detection. Raman and Electrochemical Impedance (EIS) Spectroscopies, Field Emission Scanning Electron Microscopy (FESEM) and electrochemical techniques were used to characterize and compare the CNT-modified electrodes. The results obtained revealed that the dispersion and subsequent film formation processes allow the effective non-covalent functionalization of CNT while maintaining their structural integrity and the CNT ability to facilitate the electrochemical transfer processes. Glassy carbon electrodes modified with CNT showed excellent electrochemical performance for the detection of gallic acid by Differential Pulse Voltammetry (DPV), with good sensitivity and stability. The approach was used to evaluate gallic acid content of wines (red and white) and clove (Syzygium aromaticum) without complex sample preparation. [Display omitted] •Carbon nanotubes were dispersed by non-covalent attachment of cationic reagents.•Carbon nanotube modified electrodes have been obtained from these dispersions.•Characterization was undertaken by microscopy, spectroscopy and electrochemical techniques.•CTAC/CTN films showed better electrochemical performance for gallic acid detection.•Evaluation of gallic acid content in wine and clove was achieved with these sensors.