Preparation Of Au-Ag Alloy Nanopaticles And Its Application Studies

In this paper, different size Ag-Au Alloy nanoparticles were synthesized by using citrate as protector and hydrazine as reducer. UV-Vis spectrum, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Surface Enhancement Raman Spectroscopy (SERS) were adoptted to characterize the alloy nanoparticles. We also changed the condition of reaction to fulfill the controlling the size of alloy nanoparticles. Alloy nanoparticles were assemblied on silion substrate. Then the substrate was immersed into HAuCl4 solution for different time. Using pyridine as probing molecule , we got the SERS from disposed substrate, and we also had a study on the mechanism of reaction.In UV-Vis spectrum, Au-Ag alloy colliod had only one peak of absorbance, which located between the peaks of Au and Ag. TEM analysis of our particles showed virtually uniform electron density within each particle, also supporting the notion that our nanoparticles are alloyed rather than core-shell structure. The SER spectrum of Py from alloy had different characters with that from single Au and Ag. So we can ascertain that Ag and Au atoms both exist in surface of particles, which can give us the proof to the particles belongs to alloy structure. By changing the condition of reaction, we had synthesized the Au-Ag alloy nanoparticles of 25nm, 35nm, 45nm. Furthermore we assembled alloy nanoparticles on silicon substrate, then the substrate were immersed into HAuCl4 solution. Using pyridine as probing molecule, we found that the intensity of SERS increased at first, with the time got longer ,the intensity declined gradually, At last the intensity was steady and did not change any more. By SEM,EDX and UV-Vis ,we found that in the reaction it mainly comprised three courses: pinholes formed in surface of nanoparticles,dealloy course and deposition of AgCl(s) on nanoparticles.The result has provided us the method to get better substrate for SERS and the proof to realzie the course of reaction between Au-Ag alloy and HAuCl4 solution as well.