Molecularly Imprinted Electrochemical Sensor Based on SnS₂ Nanoflower and Polyethyleneimine Modified Multiwalled Carbon Nanotubes for Highly Sensitive and Specific Detection of Diuron

The improper application of pesticides has resulted in significant environmental contamination. Therefore, determining the level of residual contamination in environmental samples is crucial. Herein, a novel molecularly imprinted polymer-based electrochemical (MIP-EC) sensor based on polyethyleneimine-modified multiwalled carbon nanotubes/tin sulfide (MWCNTs-PEI/SnS2) was developed for the sensitive and selective assay of diuron (DU) in soil samples. The MWCNTs-PEI/SnS2 was prepared by simply mixing MWCNTs-PEI and SnS2 nanoflower via ultrasonic dispersion. The as-prepared MWCNTs-PEI/SnS2 exhibited a large effective surface area, low electron transfer resistance, and superior electrocatalytic activity. Subsequently, a film of molecularly imprinted polymer (MIP) was then fabricated in situ on the MWCNTs-PEI/SnS2 modified glassy carbon electrode surface (MWCNTs-PEI/SnS2/GCE) by electropolymerization using DU as template molecule and o-phenylenediamine (o-PD) as functional monomer. Under the optimal conditions, the developed MIP-EC sensor exhibited two segments of linear relationships in the DU concentration range of 0.1–<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.0~\mu $ </tex-math></inline-formula>M (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}^{{2}} =0.997$ </tex-math></inline-formula>) and 2.0–<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$60~\mu $ </tex-math></inline-formula>M (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}^{{2}} =0.996$ </tex-math></inline-formula>) with a detection limit of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.02~\mu $ </tex-math></inline-formula>M. Besides, the proposed sensor possessed outstanding analytical performance such as superior selectivity, excellent reproducibility, and great stability. Moreover, the MIP-EC sensor has been successfully applied for DU determination in farm soil and achieved satisfactory recoveries.