Covalent organic framework encapsulated multi-walled carbon nanotubes for ultrasensitive electrochemical determination of lead ions in water and e-cigarette samples

Trace amounts of lead ions present in aqueous solutions pose significant health risks to humans. Therefore, it is crucial to develop a sensor capable of rapidly detecting trace amounts of Pb(II). We developed a material utilising covalent organic frameworks encapsulating multi-walled carbon nanotubes (Tp-Bpy-COF@MWCNTs). The physicochemical properties of Tp-Bpy-COF@MWCNTs were analysed using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR), confirming the successful encapsulation of MWCNTs by the COF. Tp-Bpy-COF@MWCNTs exhibited excellent conductivity and a porous structure. Using the Tp-Bpy-COF@MWCNT sensor for Pb(II) detection, the detection limit reached 0.0749 μg L^-1, demonstrating higher sensitivity at 0.221 μA μM^-1 cm² compared to existing technologies. Additionally, the sensor showed good recovery and repeatability for detecting Pb(II) in actual water samples, indicating its potential for Pb(II) detection applications.