Tunable electrochemical of electrosynthesized layer-by-layer multilayer films based on multi-walled carbon nanotubes and metal-organic framework as high-performance electrochemical sensor for simultaneous determination cadmium and lead

In this work, an effective strategy for the fabrication of novel layer-by-layer multilayer films modified electrodes in electrochemical sensor applications. Glassy carbon electrode (GCE) surface has been modified with various multilayer films which were prepared by continuous repeated alternating electrodeposited of carboxylated multi-walled carbon nanotubes (MWCNTs−COOH) and Zr-metal-organic frameworks (UiO-66-NH2). Newly constructed three-layer assembly of MWCNTs−COOH/UiO-66-NH2/MWCNTs−COOH/GCE as voltammetric sensor was adapted to simultaneous detection Cd2+ and Pb2+ by square-wave anodic stripping voltammetry (SWASV). Meanwhile, the formation of MWCNTs−COOH/UiO-66-NH2/MWCNTs−COOH/GCE is supported by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), X-ray photoelectron spectra (XPS), X-ray diffraction patterns (XRD), and Fourier transform infrared spectra (FT-IR), which have been researched to estimate the effect of their electrochemical detection. Here, combined the abundant adsorption sites of UiO-66-NH2 with excellent conductivity ability of MWCNTs−COOH, and the dominant characteristics of the chelation mechanisms between amine groups and heavy metal cations, which strengthened its electrocatalytic activity. Results show that three-layer film modified GCE (MWCNTs−COOH/UiO-66-NH2/MWCNTs−COOH/GCE) can acquire the optimal simultaneous detection performances as the higher sensitivities to Cd2+ (0.2528 μA ppb−1) and Pb2+ (0.3012 μA ppb−1), the lower level detection limits to Cd2+ (0.090 ppb) and Pb2+ (0.071 ppb), as well as the superior linear relativity, respectively. Finally, excellent stability, repeatability and reproducibility of three-layer film modified GCE allow this sensing platform to work in practical application. The strategy that used layer by layer electrodeposition to assemble multilayer films will provide great potential for advanced applications in environment, biomedicine, human health and energy field.