Synthesis Of Shape Controllable Gold-silver Alloy Framework Nanoparticles And The Studies Of Their SERS Activity

In recent years, increasing researches have been focused on investigating new nanostructure in the area of physics, chenmistry and materials. Hollow nanoparticles have been widely investigated, because of their unique chemical and physical properties in many areas, which are strongly size and shape dependent. For the case of their optical properties, hollow nanoparticles with different size and shape possess distict scattering and absorption properties, giving a variety of characteristic surface plasmon resonance (SPR) properties. There are mainly three aspects in this thesis as follow:1. Synthesis of Triangular gold-silver alloy nanorings in solution Triangluar silver nanoplates were synthesized by irradiating the growthsolution, which contained silver nanoseeds, silver cations, and citrate anions. The sodium lamp was chosen as the light source. The citrate anions in the system acted as both reducing agents and stabilizers. A sacrificial template reaction was used to obtain triangular gold-silver alloy nanorings by using the triangular silver nanoplates as the sacrificial template and the solution of HAuCl4 as oxidant.The process of reaction was monitored by the UV-vis spectrometer, SEM and TEM. We inspected the effect of molar ration between gold and silver on the form of triangular gold-silver alloy nanorings.2. Transform in situ for synthesis of Triangular gold-silver alloy nanorings on substrateAccording to references,all gold and gold-silver nanoparticles synthesized with sacrificial template reaction were in solution. We first transform self-assembly monolayer(SAM) of triangular nanoparticles into nanorings in situ on substrate. The XPS spectra demonstrated that the nanoframework was gold-silver alloy. The process of reaction was monitored by UV spectra and SEM. The UV spectra revealed that the SPR band was red shift along with increasing reaction time. We decreased the thickness of gold-silver alloy nanorings from 23.0 nm to 20.1 nm by varying the immersing time of substrate in the solution of HAuCl4. We measured the surface-enhanced Raman scattering (SERS) of p-aminothiophenol (P-ATP) adsorbed on gold-silver alloy nanorings monolayer. The SERS intensity was lower with decreasing the average thickness of nanorings.3. Synthesis of hexagonal nanorings and circular nanorings and their SERS activityThe silver nanodisks and hexagonal nanoparticles are synthesized by a thermal melting method, in which the triangular nanoplates were used as the original nanoparticles. The hexagonal and circular gold-silver alloy nanorings were successfully prepared via sacrificial template reaction by using hexagonal and circular nanoplates as templates and HAuCl4 as oxidant. This process was monitored by UV-vis spectra, SEM and TEM. We inspected the effect of molar ration between gold and silver on the form of hexagonal and circular gold-silver alloy nanorings. The SEM reveals that the average thickness of them were 22.3nm and 15.6nm respectively. We measured the surface-enhanced Raman scattering (SERS) of p-aminothiophenol (P-ATP) adsorbed on gold-silver alloy nanorings monolayer with different ratios between gold and silver.The SERS intensity was lower with increasing the molar ration of gold.