Intergradation of UiO‐66 Nanoparticles with Expanded Graphite for Electrocatalytic Determination of Nitrite and L‐Cysteine

Abstract In this study, metal–organic framework (MOF) nanoparticles of UiO‐66 are integrated with expanded graphite (EG) (UiO‐66/EG) by a facile solvothermal approach. The advantages of this nanocomposite UiO‐66/EG overcome the poor electronic conductivity and slow diffusion of MOFs for their electrochemical applications. Through electron microscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, and electrochemical techniques, the morphology, surface area, and physicochemical properties of this UiO‐66/EG nanocomposite are characterized. The UiO‐66/EG nanocomposite exhibits superior sensing performance over the UiO‐66 and EG when used for nitrite and L‐cysteine determination. This includes less positive oxidation potentials and enhanced oxidation currents. Using the UiO‐66/EG nanocomposite, the nitrite oxidation peak current is linear with a concentration range of 0.20 μ m to 13.15 m m with the lowest limit of detection (LOD) of 0.06 μ m ( S / N = 3). Meanwhile, superior performance is demonstrated for L‐cysteine monitoring, where the oxidation peak current is linear over the L‐cysteine concentration in the range of 0.5–250 μ m and of 0.25–3.50 m m and a LOD of 0.28 μ m ( S / N = 3). This UiO‐66/EG/GCE nanocomposite is successfully exploited to detect nitrite in food samples and to measure L‐cysteine in juice samples. Therefore, the proposed sensing platform enables the fabrication of high‐performance electrochemical sensors to accurately quantify nitrite and L‐cysteine in complex matrixes.