Construction Of Electrochemical Sensors Based On Several Novel Carbon-based Nanocomposites And Applications In Environmental And Biological Analysis

With the improvement of people's living standards,more and more attention has been paid to environmental and healthy problems,and new technical methods have continuously emerged in the fields of environmental monitoring,health examinations,and disease diagnosis.Among them,as an important analytical instrument,electrochemical sensors are often used in life sciences,medical diagnosis,food safety,and environmental protection due to their advantages of simple structure,rapid response,high sensitivity,low cost,easy miniaturization and integration.The electrode modification material is the core of constructing a high-sensitivity electrochemical sensor.Carbon nanomaterials have a special material structure and superior physical and chemical characteristics,and have the advantages of easy preparation and low cost.They have been widely used in sensor analysis,biomedicine,photoelectric catalysis,energy storage and other fields.This article is mainly based on electrochemical sensors with several different new carbon nanocomposites,and we carried out a series of electrochemical analysis studies on pesticide environmental pollutants Eserine,phenolic organic pollutant bisphenol A?BPA?and biological small molecule dopamine?DA?,the main contents are as follows:?1?Nitrogen-doped carbon black and reduced graphene oxide carbon-carbon nanocomposite?NCB@RGO?were well prepared.A highly sensitive electrochemical sensor was constructed for the detection of escherine based on the nanocomposite.By polymerizing dopamine hydrochloride on the surface of CB,then oxide graphene?GO?and polydopamine?PDA?self-assemble under electrostatic interaction,and finally undergo carbonization and reduction at high temperature to obtain NCB@RGO composite material.The materials were characterized by transmission electron microscope?TEM?,X-ray diffractometer?XRD?,Raman and electrochemical methods.The electrochemical response of Eserine on NCB@RGO/GCE was studied by cyclic voltammetry?CV?and differential pulse voltammetry?DPV?.Under optimal conditions,the linear detection range for Eserine is 0.125²5.0?M,and the detection limit is 0.035?M.The recovery rate of standard addition is maintained at 96.2%¹05.8%.?2?We introduce the concept of multi-element doping.The functional nitrogen and copper co-doped multi-walled carbon nanotubes?MWCNTs@Cu-N-C?were synthesized through a simple green laboratory method.A highly efficient electrochemical sensor is constructed on the surface of the glassy carbon electrode to detect the organic pollutant?BPA?.The materials were characterized by scanning electron microscopy?SEM?,TEM,energy spectrometer?EDS?,XRD,Raman spectrometer and electrochemical methods,respectively,confirming the successful preparation of composite materials.Then,CV and DPV were used to electrochemically detect BPA.The results of electrochemical analysis showed that the prepared MWCNTs@Cu-N-C nanocomposite has a good electrochemical response to the oxidation reaction of BPA,and the linear detection range was 0.01-100?M.The detection limit is 5.8 nM.At the same time,MWCNTs@Cu-N-C/GCE showed good reproducibility,storage stability and selectivity.?3?Polydopamine/silica?PDA/SiO₂?was obtained by spontaneous polymerization of DA on the surface of SiO₂.After carbonization under high temperature,the SiO₂was etched with sodium hydroxide to obtain hollow carbon spheres.Finally,nitrogen doped hollow carbon spheres wrapped with molybdenum disulfide nanosheets?NHCS@MoS₂?was synthesized by hydrothermal method.The materials were characterized by scanning and TEM,XRD,Raman and electrochemical impedance?EIS?methods,which proved that the materials were successfully combined.NHCS@MoS₂ utilizes the synergy of NHCS and MoS₂,enhancing the catalytic activity of the modified electrode.It has been successfully used for the electrochemical sensing of DA.The detection limit is as low as 0.022?M.The real samples tests were carried out in serum and urine,and the recovery rate of the spike was maintained at 95.5%¹08.0%.In addition,NHCS@MoS₂/GCE showed great stability,reproducibility and selectivity.