In-situ non-covalent dressing of multi-walled carbon nanotubes@titanium dioxides with carboxymethyl chitosan nanocomposite electrochemical sensors for detection of pesticide residues

Abstract In recent times, some environmental and health problems are associated with the use of pesticides, which has become a serious concern due to the damage of ecosystem and human health. Hence, it is necessary to design and develop a rapid, prompt and accurate method for determination of trace pesticides. Nanocomposite based electrochemical sensors are a powerful means to execute this task because of their highly-sensitive sensing properties allowing efficient detection of pesticide residues. In the present work, multi-walled carbon nanotubes@titanium dioxides/carboxymethyl chitosan (MWCNTs@TiO 2 /CMCS) nanocomposites were prepared by in-situ non-covalent dressing of MWCNTs@TiO 2 with CMCS moieties, while the MWCNTs@TiO 2 was prepared through in-situ sol-gel reaction of tetrabutyl titanate in the presence of MWCNTs. The nanocomposites were characterized by multiple measurement techniques, and the electrochemical properties were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The experimental results indicated that the nanocomposite modified electrodes possessed obvious redox current and reversible electrochemical properties, and could be tuned by altering the composition proportions. The fabricated sensors could be used to efficiently detect pesticide residues, presenting good linear relationship between the trichlorfon concentration and the peak current, a maximal recovery of ca 98.0% and a low detection limit of about 4.0 × 10 − 7  mol l − 1 .