Applications Of Graphene Oxide, Carbon Quantum Dots Nanocomposites In Catalytic Degradation Of Environmental Pollutants, Biological Sample Testing

With the development of nanotechnology, carbon nanomaterials with its unique physical, chemical properties and the potential applications in many fields were gradually found. The preparation of carbon nanomaterials with excellent performance and based on the application research become one of the hot topics in current study of analytical chemistry. Among them, carbon nanomaterials have the following adwantages, such as, easy prepared, high stability, good biological compatibility. They have been widely used in biological sensors, electrochemical sensors, cell imaging, biological probe and catalysis.In view of this, this dissertation was focused on the preparation and application of functionalized carbon nanocomposites in analytical chemistry.The dissertation consists of four chapters:Chapter 1 This chapter briefly introduces the developing course of carbon nanomaterials, the preparation methods and the applications in trace detection using graphene and its derivatives, carbon quantum dots, functionalized carbon nanocomposites in the fields of analytical chemistry.Chapter 2 Graphene oxide (GO) was prepared by Hummer’s method, then in the presence of 1-ethyl-3-(3-dimethyaminopropyl) carbodiimide (EDC) and N-hydroxysuccinnimide (NHS), ethylenediamine was modified on the surface of GO bying amidation reaction (GO@NH2). It was found that Cu+ could link to the surface of GO@NH2 through coordination interaction and could also reduce Au3+ into Au NPs under nitrogen protection. In view of this, a one pot in situ synthesis method of GO@NH2-Au nanocomposites (GO@NH2-Au NCs) was proposed. The method was simple, economic and fast. The as-prepared GO@NH2-Au NCs exhibited high catalytic activity in catalyzing the reduction of 4-nitrophenol (4-NP) by NaBH4. In addition, the nanocomposites were recycled nine times and its catalytic efficiency could also reach 86%.Chapter 3 Citric acid and dicyandiamide were treated by hydrothermal method to prepare nitrogen doped graphene quantum dots (N-GQDs). Chloroauric acid was reduced by N-GQDs under heating reflux. Finally, gold nanoparticles were load on N-GQDs, Au NPs-N-GQDs nanomaterials was prepared. The material has good catalytic activity in catalytic the reduction of environmental pollutants nitrophenol to aminophenol by NaBH4.Chapter 4 Silicon dioxide was generated by the hydrolysis of ethyl silicate under alkaline condition, then cadmium sulfide doped metal cadmium telluride quantum dots (CdTe/CdS) were wrapped in silica spheres. Blue light carbon quantum dots were synthesized by pyrolysis citric acid and polyethylenimine (B-PEI). In the presence of isocyanates, the carbon quantum dots were bonded on the surface of silica spheres. The dual-emission ratio fluorescent probe (CdTe/CdS@SiO2@PEI-CQDs) was prepared. By using the recognition of Cu2+ with carbon quantum dots, a new fluorescence analysis method to detect Cu2+ was established. Under the best conditions, the linear range of the method was 0-70 μM, the detection limit of 0.268 μM.