| The application of pesticides is the most economical and effective way to prevent crop diseases and insect pests.However,the environmental problems and food safety problems caused by a large number of pesticides are increasingly serious.In order to prevent and control the impact of pesticide residues on human health and ecological environment,one of the most effective methods is to strengthen the detection of pesticide residues.How to detect trace pesticide residues quickly,sensitively and selectively has become an urgent problem.Therefore,it is very important to develop a rapid,accurate and sensitive method for the detection of pesticide residues.Electrochemical analysis is the first developed instrument analysis technology,which determines the composition and concentration of substances according to their electrochemical properties and changes in solution.It has gradually become one of the most potential detection technologies due to its advantages of simple operation,high sensitivity,good selectivity and fast analysis.In this paper,the sensors based on graphene aerogel were used for electrochemical detection of pesticides,and their sensitivity,stability and selectivity were investigated.Specific content is as follows:(1)The CuO nanoparticles/graphene aerogel(CuO-NPs/GAs)composite material was synthesized by a one-step hydrothermal method.The composite material modified glassy carbon electrode was used to construct a non-enzymatic electrochemical sensor for the detection of organic phosphorus pesticide malathion.Since malathion can be specifically adsorbed on the surface of CuO,it can inhibit the redox peak of CuO.In addition,the large specific surface area of the composite material can increase the adsorption of malathion and improve the detection sensitivity.The malathion was detected under the optimal experimental conditions with a linear range of 0.03 nM to 1.5 nM and a detection limit of 1 ×10-11 M.(2)Heteroatom-doped carbon nanomaterials have proven to be good electrocatalysts in electrochemical sensing applications.β-cyclodextrin(β-CD)as a signal amplifier is also used in electrochemical sensors.Boron-doped graphene aerogel/β-CD(BGAs/β-CD)nanocomposites were designed as high-performance electrochemical sensors for electrochemical detection of Dcp.Boron doping leads to uneven charge distribution on the surface of graphene’s lattice,resulting in a large flow of π electron clouds.These flowing π electron clouds provide a large number of active sites for the catalytic oxidation of Dcp.In addition,β-CD can capture Dcp molecules through host-guest recognition,which can effectively amplify the electrochemical signal generated during the detection process.The oxidation peak current and concentration(1.0 nM～21 μM)of Dcp have a good linear relationship,and the lower detection limit is about 0.33 nM(S/N=3).This study is the preparation and three-dimensional boron-doped graphene-based composite materials.It provides a new theoretical basis for the detection of Dcp.(3)The composite materials of metal organic frameworks(MOFs)and graphene aerogels(GAs)have attracted more and more attention in the field of electrochemical sensors due to their interconnected mesoporous/macropore structure,high conductivity and large surface area.How to effectively compound the two components in a simple manner and maximize the performance of the material remains a challenge.A hierarchical porous PPy@ZIF-8/GAs was synthesized by using polypyrrole(PPy)as a cross-linking agent,and a simple in-situ growth method was proposed.First,PPy and GAs were recombined,and then ZIF-8 nanocrystals were grown orderly on the surface of PPy/GAs through the coordination interaction between Zn2+and the amino group(-NH-)group in the PPy chain.This 3D heterostructure provides an open channel for electrolyte transport and improved electron transfer between the electrode and catalyst,which is used as an electrochemical sensing platform to detect Dcp.The electrode showed high sensitivity for Dcp detection,with a detection limit as low as 0.1 nM. |
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