Multilayer Core-Sheath Structured Nickel Wire/Copper Oxide/Cobalt Oxide Composite for Highly Sensitive Non-Enzymatic Glucose Sensor

Abstract

The development of micro glucose sensors plays a vital role in the management and monitoring of diabetes, facilitating real-time tracking of blood glucose levels. In this paper, we developed a three-layer core-sheath microwire (NW@CuO@Co₃O₄) with nickel wire as the core and copper oxide and cobalt oxide nanowires as the sheath. The unique core-sheath structure of microwire enables it to have both good conductivity and excellent electrochemical catalytic activity when used as an electrode for glucose detecting. The non-enzymatic glucose sensor base on a NW@CuO@Co₃O₄ core-sheath wire exhibits a high sensitivity of 4053.1 μA mM^-1 cm^-2, a low detection limit 0.89 μM, and a short response time of less than 2 s.

Keywords: cobalt oxide nanowires; copper oxide; core-sheath; nickel wire; non-enzymatic glucose sensor.

Figure 1

(a) XRD spectrum of the NW@CuO@Co₃O₄ electrode. XPS spectra of the NW@CuO@Co₃O₄ electrode, (b) full spectrum, (c) Cu 2p spectrum, (d) Ni 2p spectrum, (e) Co 2p spectrum, and (f) O 1s spectrum.

Figure 2

(a) SEM image of pure nickel wire. (b,c) SEM image of nickel wire after “alloy/de-alloy” treatment. (d–f) SEM image of NW@CuO@Co₃O₄ electrode.

Figure 3

(a) TEM image of CuO–Co₃O₄ composite. (b) TEM image of Co₃O₄ nanowires, (c,d) TEM images of CuO nanoparticles.

Figure 4

(a) Cyclic voltammograms of pure nickel wire electrode and NW@CuO@Co₃O₄ electrode at 50 mV s⁻¹ in 0.1 M NaOH solution with and without 1mM glucose added. (b) Cyclic voltammograms of NW@CuO@Co₃O₄ electrode at 50 mV s⁻¹ in different 0.1M NaOH solutions with different concentrations of glucose added. (c) Cyclic voltammograms of NW@CuO@Co₃O₄ electrode in 0.1 M NaOH at different scan rates (25~125 mv s⁻¹). (d) Linear fitting diagram of cyclic voltammograms of oxidation peak current and reduction peak current at different scan rates and the half of the scan rate.

Figure 5

Glucose detection performance of NW@CuO@Co₃O₄ electrode (a) Current versus time curves of adding 0.5 mM glucose six times at 50 s intervals to 0.1 M NaOH solution at different voltages (0.5~0.65 V). (b) Selectivity curve after adding 1 mM glucose, ascorbic acid (AA), dopamine hydrochloride (UA), uric acid (DA), and glucose to 0.1 M NaOH solution in sequence. (c) Amperometric response curve of adding different concentrations of glucose in 0.1 M NaOH solution in sequence at 0.55 V. (d) Linear fitting diagram of current and glucose concentration in alkaline solution.

Figure 6

(a) Stability of NW@CuO@Co₃O₄ glucose sensors in 0.1 mM glucose solution. (b) EIS curves of NW and NW@CuO@Co₃O₄. (c) Current responses of five NW@CuO@Co₃O₄ electrodes in 0.1 M NaOH with 2 mM glucose at 0.55 V.