Construction And Application Of Enzyme-Free Sensors Based On Three Kinds Of Silver Nano Composites

The applicationg value of Ag nano-materials is of great importance due to their various proper physical and chemical properties. In this paper, it is succeed in making three newfashioned Ag nanocomposites materials and three types of enzyme-free electrochemical sensors for hydrogen peroxide. In addition, it is studied on the relationship between the microstructure of nanocomposites and the electrochemical performance as well as established new methods for the detection of hydrogen peroxide. In a sense, this reasearch enriches the contents of electrochemical sensors and broaden the application field of Ag nanomaterials. The thesis consisted of four chapters and the main contents were summarized and presented as follows:1. ZnO rods and ZnO spheres can be synthesized by the means of changing the concentration of citric acid to regulate the growth of ZnO crystal face; then the AgNPs was attached to the surface of ZnO through a chemical process; finally, enzyme-free hydrogen peroxide sensor based on Ag-ZnO (spherical) was fabricated. This reasearch found that compared with the ZnO rods, ZnO spheres can attached more Ag nanoparticles and give greater electrocatalytic capacity for H2O2. The electrochemical experiments results indicate that Ag-ZnO/GCE has a significant catalytic on H2O2. There are a favourable linear relationship (r=0.9997) between the catalytic current signal and the concentration of H2O2when it is at the range of1.0x10-5～1.5x10-2mol·L-1, the detection limit is3.3x10-6mol·L-1(S/N=3), the sensitivity is31.41μA·(mmol-L-1)-1·cm-2.2. Ag@AgCl Hollow cubes were synthesized through water-soluble template method and photo-reducton process. The growth mechanism and electrochemical behaviors was investigated, and the Ag@AgCl/GCE enzyme-free hydrogen peroxide sensor was fabricated. The electrochemical experimental results show that this sensor can detect H2O2by chronoamperometry at lower work potential (-0.1V), and it presents a nice linear relationship(r=0.9998) between the current signal and the concentration of H2O2when it is at the range of5.0x10-6～1.5x10-2mol·L-1, the detection limit is1.7x10-6mol·L-1(S/N=3)and the sensitivity is88.79μA·(mmol·L-1)-1·cm-2.3. Ag-PDA-CB composite materials was prepared successfully by using dopamine to change the hydrophilicity of carbon black and its electrochemical behaviors and electrocatalytic properties was studied, then the enzyme-free hydrogen peroxide sensor Ag-PDA-CB/GCE was fabricated and established a new method to detect H2O2. The results show that the sensor presents a nice linear relationship between the catalytic current signal and the concentration of H2O2when it is at the range of1.0×10-6～4.8×10-3mol·L-I, the detection limit is3.3×10-7mol·L-1(S/N=3), the sensitivity is155.71μA·(mmol·L-1)-1·cm-2.