Co/Zn ZIFs with MXene and MWCNTs nanocomposites for electro-detection of nitrite ions: Effect of composite substrate

Abstract

This work introduces an electrochemical sensor designed for detection of nitrite ions using multi walled carbon nanotubes bimetallic zeolitic imidazole frameworks (MWCNTs-Co/Zn ZIFs) and MXene-Co/Zn ZIFs modified carbon ceramic electrodes (CCE) through a one-step electrochemical process. The pHysiochemical characterizations of modified electrodes were investigated by using X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, energy dispersive X-ray and electrochemical methods. Cyclic voltammetry and chronoamperometry techniques were used to assess the electrochemical performance of the modified electrodes toward oxidation and determination of nitrite ions. Both of the MWCNTs-Co/Zn ZIFs/CCE and MXene-Co/Zn ZIFs/CCE show high electrocatalytic activity for oxidation of nitrite ions in neutral media (pH = 7.0). Owing to the fascinating synergy between the intrinsic two-dimensional MXene and Co/Zn-ZIFs, the MXene-Co/Zn-ZIFs/CCE shows better electrocatalytic activity than the MWCNTs-Co/Zn ZIFs/CCE. The selected sensor, MXene-Co/Zn ZIFs/CCE, exhibits a linear response range from 2 to 500 μM, LOD (1.6 μM), LOQ (5.5 μM) and sensitivity (1.80180 μA mM⁻¹ cm⁻²). Moreover, this sensor retains 96.77 % of its initial response after 25 days of storage at room temperature in the laboratory. Finally, the MXene-Co/Zn ZIFs/CCE was used for determination of nitrite ions in real samples with satisfactory results which suggests that the constructed sensor has high potential application in food samples analysis.