Construction Of Graphene-based Electrochemical Sensors And Its Application In Drug And Environmental Analysis

Graphene has a large specific surface area,excellent electrical properties,good biocompatibility and mechanical strength,which makes it unique in the construction of electrochemical sensors and become a research hotspot in the field of electrochemical sensing.The modified electrode prepared on the basis of graphene-based composite material can maintain the activity of graphene and the loaded material,and improve the load capacity of the electrode.The synergistic effect between the composite materials accelerated the redox reaction of target analyte,improving the detection sensitivity of the electrochemical sensor.This thesis aims to use graphene as the base material to prepare modified materials combining with various functional materials?metal oxides,metal organic frameworks,noble metal nanoparticles,porous cyclodextrin polymers,etc.?,which reduce the degree of aggregation of graphene,increase the active surface area of composites and improve the catalytic activity,conductivity and stability of composites.And based on this,several electrochemical sensors were contructed with excellent performance for drug analysis and environmental detection.The main research is expressed as follows:?1?A new nanocomposite,ruthenium oxide-poly?dimethyldiallylammonium chloride?-reduced graphene oxide?RuO₂-PDDA-rGO?,was synthetized by a one-step method.The bare glassy carbon electrode was modified with the RuO₂-PDDA-rGO to construct a novel electrochemical sensor and used for the detection of baicalein.The electrochemical reaction of baicalein on the sensor surface was studied,and the reasonable reaction mechanism was deduced.The linear response of the constructed electrochemical sensor to baicalein ranged from 2 nM to 400 nM with a detection limit of 0.6 nM?S/N=3?.At the same time,the electrochemical analysis method was successfully applied to the determination of baicalein in baicalein aluminum capsules with satisfactory results.?2?Agold-silver-platinumnano-alloycrystal-porouscyclodextrin polymer-graphene oxide composite?AuAgPt-PCD-GO?was synthesized and used to modified the bare glassy carbon electrode.A new electrochemical sensor was constructed and used for simultaneous detection of bisphenol A and bisphenol S.The sensor had good electrochemical response to bisphenol A and bisphenol S,and the linear response ranges from 6 nM⁴000 nM and 8 nM⁸000 nM,respectively,with the detection limits of 2 nM and 2.67 nM?S/N=3?.The sensor was used for actual sample analysis and the results were satisfactory.?3?A sandwich type MOF?M@Pt@M-rGO?was successfully synthesized in-situ on the surface of reduced graphene oxide.The morphology,structure and electrochemical properties of materials were characterized by physical and electrochemical means.The electrochemical sensor was constructed based on M@Pt@M-rGO modified material and successfully used for the simultaneous detection of hydroquinone,catechol and resorcinol.The linear response range of hydroquinone,catechol and resorcinol were 0.05?M²00?M,0.1?M¹60?M and0.4?M³00?M,and the detection limits were 0.015?M,0.032?M and 0.133?M,respectively?S/N=3?.In addition,the sensor was successfully used to detection the content of isomers in river and lake water samples.