In-situ insertion of multi-walled carbon nanotubes in the Fe3O4/N/C composite derived from iron-based metal-organic frameworks as a catalyst for effective sensing acetaminophen and metronidazole.

In this paper, a novel Fe3O4/N/C@MWCNTs composite derived from iron-based metal-organic frameworks (H2N-Fe-MIL-88B) with multi-walled carbon nanotubes (MWCNTs) was prepared successfully through a simple calcination process. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and electrochemical measurements were employed to comprehensive characterize the composites. Compare with the physical mixture, in-situ insertion of MWCNTs in the Fe3O4/N/C formed Fe3O4/N/C@MWCNTs composite has the higher conductivity, larger BET surface area and more satisfying electrocatalytic properties. Meanwhile, this composite with the reasonable combinations exhibits remarkable electrocatalytic activities for acetaminophen (AP) and metronidazole (MNZ) due to the synergistic interaction between the components. Thus, the Fe3O4/N/C@MWCNTs-2-600-based electrochemical sensor was established to effectively detect these two medicine molecules, respectively. In the optimized test conditions, the proposed sensor exhibits a wide linear response (0.5-5.0 μM and 5.0-1355.0 μM) for AP and the limit of detection (LOD) was achieved to be 0.14 μM (S/N = 3). Meanwhile, this sensor also shows two linear relationships with the concentration of MNZ in the range of 1.0 μM to 10.0 μM and 10.0 μM to 725.0 μM with the LOD of 0.19 μM (S/N = 3). Moreover, the satisfactory results were also acquired when the proposed sensor was used for the determination of AP and MNZ in the human serum and urine, demonstrating great promising of this electrochemical sensor for clinical applications.