Binary nanocomposite based on Co3O4 nanocubes and multiwalled carbon nanotubes as an ultrasensitive platform for amperometric determination of dopamine

Composites containing cobalt oxide (Co3O4) nanocubes integrated with multiwall carbon nanotubes (MWCNT) were synthesized by a hydrothermal route. The fractions of MWCNTs in the composite were varied from 4, 8, 12, 16 and 20 wt.%, and the resulting materials are denoted as C1, C2, C3, C4 and C5, respectively. The formation of products with high structural crystallinity was confirmed by X-ray photoelectron spectroscopy, Raman spectroscopy and X-ray diffraction. A morphological study by field emission scanning electron microscopy and high resolution transmission electron microscopy showed the successful integration of Co3O4 nanocubes to the MWCNTs with an average particle size of similar to 32 nm. The surface of a glassy carbon electrode (GCE) was modified with the nanocomposites in order to evaluate the electrochemical performance of the nanocomposites. Cyclic voltammetry showed that the C4-modified GCE displays best performance in terms of oxidation potential and peak current in comparison to that of a bare GCE, Co3O4 nanocubes, or GCEs modified with C1, C2, C3 or C5. The detection limit (at an S/N ratio of 3) is 0.176 nM by using chronoamperometry, and the linear range is between 1 and 20 mu M.