Detection Of Copper Ions By Paper-based Electrochemiluminescence Sensor Based On Carbon-based Quantum Dots And Their Composites

With the development of the science and technology industry,heavy metal pollution has caused a great impact on people’s living health.It has become a problem that we should pay attention to realize portable outdoor detection conveniently,quickly,and accurately.In this thesis,a paper-based sensor is prepared,using electrochemiluminescence（ECL）detection technology,using carbon-based quantum dots as the luminous material,to complete the linear sensing of copper heavy metal ions.The paper-based sensor is more convenient to prepare,and some problems such as the amplification of the ECL signal of carbon-based quantum dots are solved.This thesis is divided into the following five chapters:The first chapter introduces the basic system and reaction mechanism of ECL,as well as the development prospects of ECL technology;then,the preparation of existing carbon-based quantum dots,as well as the characteristics and applications of ECL are analyzed and introduced,and investigate the existing carbon-based quantum dots composite materials;secondly,summarize the preparation and application of portable paper-based ECL sensors;then explain the hazards of copper ions and the significance and methods of detection;finally,summarize this article the main research ideas and content.The second chapter the paper-based hydrophobic channel is constructed by screen printing technology.By observing the filter paper treated with three kinds of hydrophobic materials,the hydrophobic performance of different hydrophobic materials on the filter paper was evaluated in terms of hydrophobicity,maintenance time and resolution.After comparison,it was determined that the combination of ethyl cellulose and terpineol is a very simple and well-hydrophobic slurry,and the screen printing technology is used to complete the printing of the hydrophobic pattern of the hydrophobic slurry on the paper to complete the construction of the hydrophilic and hydrophobic channels.And the performance of the hydrophobic slurry after heating time and long-term storage was studied,and finally proved the feasibility of ethyl cellulose and terpineol as the first step of preparing paper-based sensors as the hydrophobic slurry.Paper-based ECL sensors and trace detection provide a good foundation.The third chapter,nitrogen-doped carbon quantum dots（N-CQDs）were used to detect Cu²⁺ions on paper-based sensors.First,carbon-based quantum dots（CQDs）and N-CQDs were prepared by a one-step hydrothermal method.A series of characterizations proved the successful preparation of N-CQDs.The paper-based chip electrode was prepared by screen-printing technology.By modifying the quantum dots on the working electrode and forming a co-reactant system with potassium persulfate（K₂S₂O₈）for ECL detection,it proved that the N-CQDs were better than those without doping.The ECL performance of CQDs has been improved.Through the use of N-CQDs modified paper-based ECL sensor to complete the sensing of Cu²⁺ions,Cu²⁺ions can enhance the ECL of the N-CQDs-K₂S₂O₈ system,showing overall excellent ECL stability,reproducibility,and selectivity,with a wide linear relationship ranging from 0.01-1000μM.The fourth chapter carry out the ECL signal amplification effect of the paper-based working electrode modified by the composite material formed by the combination of ZnO and N-CQDs,and the sensing of Cu²⁺ions.By using the pyrolysis method,N-CQDs with glucosamine as the carbon source and urea as the nitrogen source were prepared,and the N-CQDs/ZnO composites prepared by adding zinc acetate,in the same way,were subjected to a series of characterization,which verified the N-CQDs/ZnO composites.The prepared CQDs/ZnO composite materials were modified for the ECL test,which proved its enhancement effect on ECL signal.The composite material was modified on a paper-based electrode to detect Cu²⁺ions,the system produced quenching reaction due to the recombination of ZnO,and the paper-based ECL sensor improved the linear correlation based on the wide linear detection range.The fifth chapter summarizes the contents of this paper,analyzes the problems existing in the current research methods,and puts forward the prospect of the next research plan,hoping to make a meaningful contribution to the practical application of portable paper-based ECL devices in the future.