A facile one-step electrochemical fabrication of reduced graphene oxide–mutilwall carbon nanotubes–phospotungstic acid composite for dopamine sensing

A novel one-step electrochemical method is developed to fabricate the composite of reduced graphene oxide–mutilwall carbon nanotubes–phospotungstic acid (RGO–MWNTs–PTA) on electrodes and used for the detection of dopamine (DA) in the presence of high concentrations of ascorbic acid (AA). Comparing with RGO, PTA, RGO-PTA, RGO–MWNTs, MWNTs–PTA modified electrodes, the RGO–MWNTs–PTA modified electrode is more sensitive and selective to DA due to a synergistic effect. The synergistic effect results from: (i) the enlarged area of electrodes due to the intercalation of mutilwall carbon nanotubes between the stacked reduced graphene oxide with associated large electrochemical active sites and 3D nano-structured RGO–MWNTs covered by numerous PTA particles; (ii) the improved conductivity through the formation of a 3D network aided by mutilwall carbon nanotubes; (iii) the accelerated electron transfer rates which is due to aromatic π–π stacking and electrostatic attraction between positively-charged DA and negatively-charged RGO–MWNTs–PTA-modified electrode. The sensing performance of RGO–MWNTs–PTA-modified electrode is investigated by differential pulse voltammetry (DPV), revealing a linear range of 0.5–20 μM with a detection limit of 1.14 μM (3σ method).