Solid-Phase Microwave Synthesis of Nickel Sulfide/Nickel Oxide/Carbon Nanotubes for the Electrochemical Determination of Melamine by Differential Pulse Voltammetry (DPV)

A rapid and simple solid-state microwave method was used for the synthesis of a ternary nanocomposite comprising nickel sulfide/nickel oxide/carbon nanotubes (NiSx/NiO/CNT). This nanocomposite was subsequently utilized for the electrochemical determination of melamine. Various techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX), X-ray diffraction (XRD), and Raman spectroscopy, were employed to characterize the structure and morphology of the material. Additionally, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were utilized to investigate the electrochemical properties. The results indicated that the NiSx/NiO/CNT nanocomposite electrode demonstrated a favorable electrochemical reactivity toward melamine. It displayed a linear range from 10 to 2000 μg/L, a detection limit (DL) as low as 0.017 μg/L, and a sensitivity of up to 83.5 μA/(μM·cm2). The NiSx/NiO/CNT composite demonstrated the ability to detect trace melamine in milk samples, demonstrating its practical application.