Dopamine sensor based on a hybrid material composed of cuprous oxide hollow microspheres and carbon black

We report on a novel electrochemical dopamine (DA) sensor based on a glassy carbon electrode (GCE) modified with a hybrid material composed of Cu(I) oxide hollow microspheres and carbon black. The hybrid material was synthesized in a mixed solvent composed of water and the deep eutectic solvent choline chloride/urea, and by in-situ reduction of Cu(II) by ascorbic acid. The surface morphology and structure of the materials were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Cyclic voltammetry and chronoamperometry were used to evaluate the electrocatalytic properties of the modified GCE toward DA oxidation in phosphate buffer solution of pH 5.7. The sensor displays a higher electrocatalytic activity toward DA oxidation compared to other modified electrodes. At a working potential of 0.25 V (vs. SCE), the sensor exhibits a rapid response (< 3 s) and a wide linear range from 9.9 x 10(-8) to 7.08 x 10(-4) mol L-1. The detection limit is as low as 3.96 x 10(-8) mol L-1 (S/N = 3). In addition to its high sensitivity, the sensor displays good reproducibility, long-term stability and fair selectivity.