Carbon nanotube/reduced graphene oxide thin-film nanocomposite formed at liquid-liquid interface: Characterization and potential electroanalytical applications

Abstract

This paper presents a new route to produce carbon nanotube/reduced graphene oxide (CNT/rGO) nanocomposites using the interfacial method to produce high-performance electroanalytical sensing. The nanocomposite thin-film is formed at the cyclohexane/water immiscible interface after stirring of a mixture of CNT and rGO in the biphasic solution and can be transferred to any planar substrate. As a proof-of-concept, the nanocomposite film was transferred to a boron-doped diamond electrode, which was compared with glassy-carbon and gold substrates. Improved electrochemical sensing of model phenolic compounds (dopamine and catechol) under stationary (cyclic voltammetry) and flow (amperometry) conditions was verified in comparison with unmodified and modified surfaces with rGO and CNT using the same method. Electrochemical impedance spectroscopy and heterogeneous electron transfer rate constant (k0) values also evidenced the faster electron transfer for a redox probe on the nanocomposite surface, while the increase in electroactive area by CNT/rGO was minimal in comparison with CNT or rGO (6–12%). Scanning electron microscopic images show the interaction of rGO with CNT and Raman spectra revealed the defect density. Amperometric detection of phenolic compounds showed synergistic properties of CNT and rGO on the response of nanocomposite, which resulted in highly sensitive sensors with superior performance in comparison with electrochemical sensors based on CNT or rGO already reported (nanomolar detection limits for dopamine and catechol). Dopamine determination in serum samples was demonstrated. Hence, this new protocol offers great promises to develop improved electrochemical sensors for a wide range of analytes.