Reduced graphene oxide functionalized with a CoS/ionic liquid composite and decorated with gold nanoparticles for voltammetric sensing of dopamine.

A nanohybrid electrode was prepared by functionalizing reduced graphene oxide nanosheets (GNs) with gold nanoparticles (AuNP), CoS, and an ionic liquid. It is shown to enable voltammetric determination of dopamine (DA). The AuNPs were electrodeposited onto the electrode that was first modified with CoS and the IL-GNs to obtain a well-defined 3-dimensional and porous structure. The nanohybrid material displays high catalytic activity and an ultrasensitive cyclic voltammetric response to DA. The peak current (best measured at a working voltage of 0.17 V vs. Ag/AgCl) increases linearly in the 0.1 to 400 μM DA concentration range, with a 40 nM detection limit (at S/N = 3). The electrode was successfully applied to the determination of DA in spiked serum samples. Graphical abstract Schematic of the preparation of a nanohybrid electrode odified with graphene oxide nanosheets functionalized with gold nanoparticles/CoS/ionic liquid by electrodeposition. The electrode exhibits excellent electrocatalytic performance with respect to the electrochemical detection of dopamine. The determination of the DPV curves provides satisfactory results which can be characterized by a linear response for DA concentrations ranging from 0.1 to 400.0 μM with a 40 nM detection limit (at S/N = 3).