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

Abstract

In this work, NiCo2S4 nanosheet-decorated Cu7S4 hollow microcubes were synthesized by electroless deposition and hydrothermal techniques for electrochemical determination of glucose in human serum. First, Cu2O cubes were synthesized at room temperature by electroless deposition, while the NiCo precursors (NiCo2O4 nanosheets) were grown using the hydrothermal process. Afterward, a Cu7S4–NiCo2S4 composite was synthesized via one-step vulcanization of Cu2O and NiCo2O4 using Na2S. The crystal structure, elemental valence state, and morphology of the synthesized Cu7S4–NiCo2S4 composite were investigated using X-ray diffraction, X-ray photoelectron energy spectroscopy, scanning electron microscopy, and transmission electron microscopy. Note that the hollow-structured Cu7S4 can not only serve as the substrate for NiCo2S4 nanosheets to enhance the specific surface area but also promote the electron transfer and improve the electrocatalytic activity of the Cu7S4–NiCo2S4 composite. By optimizing the experimental parameters of the applied potential, the amount of Cu7S4–NiCo2S4 composite, and the concentration of NaOH solution, the Cu7S4–NiCo2S4-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.