Determination of dopamine using a glassy carbon electrode modified with a graphene and carbon nanotube hybrid decorated with molybdenum disulfide flowers

We describe a hybrid material that consists of molybdenum sulfide flowers placed on graphene nanosheets and multiwalled carbon nanotubes (GNS-CNTs/MoS2). It was deposited on a glassy carbon electrode (GCE) which then is well suited for sensitive and selective determination of dopamine. The GNS-CNTs/MoS2 nanocomposite was prepared by a hydrothermal method and characterized by scanning electron and transmission emission microscopies, energydispersive X-ray spectroscopy, cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy. Electrochemical studies show the composite to possess excellent electrochemical properties such as a large electrochemically active surface, high capacitance current, a wide potential window, high conductivity and large porosity. The electrode displays excellent electrocatalytic ability to oxidize dopamine. The modified GCE, best operated at a working potential as low as 0.15 V (vs. Ag/AgCl), responds linearly to dopamine in the 100 nM to 100 mu M concentration range. The detection limit is 50 nM, and the sensitivity is 10.81 (+/- 0.26) mu A.mu M-1.cm(-2). The sensor has good selectivity, appreciable stability, repeatability and reproducibility. It was applied to the determination of dopamine in (spiked) biological and pharmaceutical samples.