Synthesis Of Ag Nanoparticles And Its Application In Electrochemical Sensors

Electrochemical sensors are active and promising in the analytical chemistry fields. In the theses, we focused our studies on silver nanoparticles (Ag NPs) electrodeposited on poly (ferrocenylsilane) (PFS)-DNA-modified electrode, Ag NPs electrodeposited on DNA-MWCNTs modified electrode and Ag NPs electrodeposited on Polyphenylenediamine (PoPD)-modified electrode and developed the corresponding electrochemical sensors. This work mainly covered the following areas.1. The first part focused on studying Ag NPs electrodeposited on three-dimensional (3D) PFS-DNA networks to produce 3D Ag NPs networks and accordingly developed a novel hydrogen peroxide (H₂O₂) sensor. It was very important that PFS and DNA could form 3D porous configuration and accordingly improve the electron and electrolyte ion transfer obviously. Compared to some previous works, the resulted sensor showed a superior electrocatalytic behavior to the reduction of H₂O₂.The layer of PFS-DNA, electrodeposition time of Ag NPs and the pH of PBS influenced the electrochemical behaviors of Ag NPs/(PFS-DNA)n/GCE. DNA played an important role as an intermediate for the absorption of PFS and electron transfer.2. The second part was concentrated on Ag NPs electrodeposited on DNA-MWCNTs composites modified GCE and their applications as a H₂O₂ sensor. Scanning electron microscope (SEM) images showed that many small Ag NPs formed and uniformly distributed on the DNA-MWCNTs composites/glassy carbon electrode (GCE). We found that the DNA-MWCNTs composites could control the growth of Ag NPs and the Ag NPs were well-distributed. Meanwhile, the electrochemical experiments proved that the Ag NPs had an excellent catalytic ability to reduction of H₂O₂, suggesting that they could be used as a sensor to determinate H₂O₂. The catalytic activity of Ag NPs was ascribed to DNA-MWCNTs composites that resulted in the homogenous distribution of many small Ag NPs and accordingly depended on the the volumes ratio of DNA and MWCNTs, electrodeposition time and the pH of the buffer solution.3. The third part was about a novel H₂O₂ sensor based on Ag NPs electrodeposited on PoPD film with 3D porous structure modified GCE. In this part, we have exploited Ag NPs electrodeposited on PoPD film that were polymerized on a cleaned glassy carbon electrode by potential cycling as an electrocatalyst to fabricate a H₂O₂ sensor. The Ag NPs electrodeposited on three-dimensional PoPD film showed very good catalytic ability for the reduction of H₂O₂. The well catalytic activity of the electrode was ascribed to the PoPD film with 3D porous structure that resulted in the formation of small Ag NPs and the homogenous distribution of Ag NPs.