NiCo₂S₄ Nanosheets Supported on Cu₇S₄ Microcubes for the Electrochemical Detection of Glucose in Human Serum

In this work, NiCo 2 S 4 nanosheet-decorated Cu 7 S 4 hollow microcubes were synthesized by electroless deposition and hydrothermal techniques for electrochemical determination of glucose in human serum. First, Cu 2 O cubes were synthesized at room temperature by electroless deposition, while the NiCo precursors (NiCo 2 O 4 nanosheets) were grown using the hydrothermal process. Afterward, a Cu 7 S 4 –NiCo 2 S 4 composite was synthesized via one-step vulcanization of Cu 2 O and NiCo 2 O 4 using Na 2 S. The crystal structure, elemental valence state, and morphology of the synthesized Cu 7 S 4 –NiCo 2 S 4 composite were investigated using X-ray diffraction, X-ray photoelectron energy spectroscopy, scanning electron microscopy, and transmission electron microscopy. Note that the hollow-structured Cu 7 S 4 can not only serve as the substrate for NiCo 2 S 4 nanosheets to enhance the specific surface area but also promote the electron transfer and improve the electrocatalytic activity of the Cu 7 S 4 –NiCo 2 S 4 composite. By optimizing the experimental parameters of the applied potential, the amount of Cu 7 S 4 –NiCo 2 S 4 composite, and the concentration of NaOH solution, the Cu 7 S 4 –NiCo 2 S 4 -modified glassy carbon electrode demonstrates a good linear relationship with glucose concentrations in the ranges of 0.002–0.3 and 0.3–20 mM, with sensitivities of 430 and 162 μA mM –1 cm –2, respectively. The detection limit is 0.4 μM ( S / N = 3). The proposed sensor exhibits remarkable performance in detecting the glucose content in human serum, implying its immense practical potential.