The Preparation Of G-C₃N₄ Composite And Its Application In Electrochemical Sensor

With the improvement of living standard,more and more people pay attention to themselves health and environment protection.Thus,it is necessary to develop the novel analytical sensing technology,which could be applied in environment monitoring and health assessment.The electrochemical sensor has attracted increasing interest due to its high-sensitivity,excellent-selectivity,low-cost and easy-to-operation.The key to design electrochemical sensor with excellent properties is the development of advanced materials with excellent electrochemical performance,good stability and low price.In this dissertation,different g-C₃N₄and its composites were prepared by various method and the relationship among method,morphology,chemical composition and electrochemical performance was further discussed.The details of this research are divided into the following six chapters.(1).The g-C₃N₄ nanosheets were prepared by calcination treatment(T-C₃N₄)and protonation process(H-C₃N₄)and the effects of different methods on the morphology,chemical structure and electrochemical properties were further investigated by characterization and electrochemical experiment.Based on the g-C₃N₄ nanosheets prepared by protonation process,a novel ratiometric electrochemical detection platform for quercetin,which exhibited high selectivity and sensitivity to quercetin.(2).Based on the g-C₃N₄ nanosheets prepared by calcination treatment,the introduce of gold nanoparticle(Au NPs)had been achieved by different method:in-situ growth and self-assembly.The characterization and electrochemical experiments were carried out to further investigate the relationship between loading methods and morphology,chemical composite and electrochemical performance of materials.Based on the self-assembly method,g-C₃N₄ nanosheets loaded with Au NPs was prepared and this composite was used to design a novel electrochemical sensor for riboflavin,which presented high selectivity,good sensitivity excellent repeatability and stability.(3).The enhancement of conductivity could improve the electrochemical performance of g-C₃N₄,thus H-C₃N₄ and Ti₃C₂T_x were recombined together(H-C₃N₄/Ti₃C₂T_x)by electrostatic self-assembly.Then,the composite was used to prepare the electrochemical sensor for simultaneous detection of Pb²⁺and Cd²⁺,which showed excellent sensitivity with low limit of detections were 0.6 n M and 1.0 n M,respectively.And,this electrochemical detection platform exhibited good selectivity,stability and reproductivity.In addition,the difference between individual and simultaneous detection could be derived from the formation of intermetallic compound and the competition between Pb²⁺and Cd²⁺.(4).With the help of electrostatic self-assembly and ice-crystal template,Au-Pd NPs were introduced into the H-C₃N₄/Ti₃C₂T_x(Au-Pd/H-C₃N₄/Ti₃C₂T_x).The electrochemical and physical performance of this nanocomposite was investigated by various electrochemical experiments and characterizations.Based on Au-Pd/H-C₃N₄/Ti₃C₂T_x,a novel electrochemical sensor was prepared for the simultaneous detection of riboflavin and quercetin and exhibited excellent sensitivity.Then,the mathematical matrix model about the concentration and current response of riboflavin and quercetin were constructed to achieve the simultaneous quantitative detection.