Facile synthesis and dopamine sensing application of three component nanocomposite thin films based on polythiophene, gold nanoparticles and carbon nanotubes

A simple and versatile route to synthesize nanocomposite thin films containing polythiophene, gold nanoparticles and carbon nanotubes is demonstrated. The strategy is based on a liquid-liquid interfacial reaction, in which polythiophene and gold nanoparticles are concomitantly synthesized through a reaction between an aqueous solution of tetrachloroauric acid and a n-hexane solution of thiophene containing carbon nanotubes previously dispersed. The three-component nanocomposite is obtained directly as a thin and homogeneous film, self-assembled at the liquid-liquid interface, and easily transferable to ordinary substrates. Different reaction times were investigated, and the materials were characterized by several techniques, such as SEM, TEM, profilometry and EDS to inform about the morphology and the elementary composition, FTIR, Raman, TGA, UV–Vis and DRX about the structure of the materials and the electrochemical properties were investigated by cyclic voltammetry. The presence of carbon nanotubes accelerates the reaction, yielding greater amount of product when compared to similar reactions conducted without the carbon nanotubes. The proportion between the components, amount of products and film thickness can be controlled by the reaction time. It is observed that the amount of both polythiophene and gold nanoparticles increases with the increasing reaction time, inducing the formation of polymer agglomerates over de carbon nanotubes and the anisotropic growth of gold nanoparticles. The presence of CNT increases the electrochemical stability of the films when compared to similar ones without CNT. The potentiality of the prepared nanocomposite as electrochemical sensor was evaluated for voltammetric determination of dopamine. Best results were found for a PT/Au/CNT film prepared after 4.5 h of reaction, with a limit of detection of 0.69 μmol L−1.