Preparation Of Zirconium-based Sensing Materials And Its Application In Methyl Parathion Detection

Methyl parathion（MP）is a widely used organophosphorus pesticide with high neurotoxicity.The benzene ring structure of their metabolic intermediates can remain in the environment for a long time,posing a great threat to human health.It has been reported that chronic exposure to MP at 2 mg/L can cause a variety of adverse health effects in organisms,including immune deficiency,carcinogenicity,mutagenicity,reproductive toxicity,and endocrine disrupting effects.At present,the MP detection methods mainly include Raman spectroscopy,gas chromatography-mass spectrometry,high-performance liquid chromatography,and chemiluminescence.Although the above-mentioned methods can detect MP sensitively and selectively,they are greatly restrained in practice owing to the complicate operation and expensive cost.By comparison,electroch emical analysis is an attractive one with the advantages of compact and simple operation.Therefore,it is a great challenge to design an electrochemical sensing material with the advantages of low cost,high sensitivity,and strong selectivity.In this work,we aim to design and synthesize inexpensive,highly sensitive and selective electrochemical sensing materials with functional zirconium-based materials.Through the three aspects of material surface modification,material functional layer mod ification and material structural functionalization,the electrochemical sensing materials with low cost and high sensing performance were synthesized by simple methods,and satisfactory results were achieved in the MP spiked detection of actual river water samples.（1）Zr（OH）₄/Nafion films with excellent dispersion were prepared by a simple co-precipitation method at room temperature,and the composites were rich in hydroxyl groups.The Zr（OH）₄nanoparticles with strong adsorption effect on MP were uniformly loaded on the Nafion films with excellent ion mobility.UV-Vis and electrochemical tests showed that the Zr（OH）₄/Nafion composite films combined the advantages of both substances,with high ion mobility and a large number of adsorption active sites.The optimization results showed that the Zr（OH）₄-6/Nafion film exhibited stronger sensing performance for MP compared to other controls,with a detection limit of 8.82 ng m L^-1 for MP in the range of 50～4000 ng m L^-1.（2）In order to overcome the limitation of sensor sensitivity due to poor electrical conductivity,Ti₃C₂T_x functional layer modification was performed based on Work 1.The large layer spacing Ti₃C₂T_x functional layer and Zr（OH）₄ nanoparticles were constructed into an organ-like sandwich structure by chemical etching process.The prepared Zr（OH）₄/Ti₃C₂T_x sensing material inherited the strong affinity of Zr（OH）₄ nanoparticles for MP,while the conductivity and sensing performance were significantly improved,and the detection limit of MP was increased to 2.86 ng m L^-1 in the detection range of 50～4000 ng-m L^-1.（3）The PEDOT/YSZ@r GO fibers sensing material was synthesized by electrostatic spinning,reducing atmosphere heat treatment and electrodeposition,thus further functionalizing the structure of the sensing material.The results of electrochemical tests,UV-Vis tests and DFT calculations showed that the Y-doping and the composite r GO not only improved the electrical conductivity of zirconia but also enhanced the adsorption ability of MP.The surface area of the sensing material was greatly increased,and the effective active sites were increased.Finally,the electrodeposition technique was used to load PEDOT on the surface of YSZ@r GO fibers to further improve the electrochemical activity of the sensing material.The electrochemical test results show that the charge transfer impedance of PEDOT/YSZ@r GO/SS electrodes is only 9.19Ωand the electrochemical active area is as high as 10.66 cm².Under the optimal conditions,PEDOT/YSZ@r GO/SS has a wide MP detection range of 5～4000 ng m L^-1 and a detection limit as low as 1.57 ng m L^-1,which is better than most reported MP electrochemical sensors.