Preparation Of Metal-Semiconductor SERS Substrate And Its Application In Detection Of Organic Molecules

In recent years, water pollution has become a serious social issue due to its serious damage to the development of society and economy even people’s health. For accidental water pollution incidents, it is essential to develop a fast and easy method to detect and identify low concentration of pollution molecule. The result is important for reducing pollution diffusion and removing pollutants molecules. Surface-enhanced Raman spectroscopy (SERS) is an Analytical technique which has many advantages, such as: rapid detection, high sensitivity, low demand on the sample preparation. So it is a potential analytical method for organic pollutants detection. In this thesis we attempt to employ simple, rapid methods to prepare metal-semiconductor composite such as Ag2S-Ag、CuO-Ag. As SERS substrate, the metal-semiconductor composite can keep not only high SERS activity of Au、Ag nanoparticles but also high photocatalytic activity. We study the SERS activity a of Ag2S-Ag、CuO-Ag. The main work is follows:(1) We employ microwave-assisted synthesis method for preparing Ag2S-Ag nanorods. The as-prepare Ag2S-Ag nanorods were characterized by scanning electron microscopy(SEM), UV-visible absorption spectroscopy(UV-Vis), X-ray powder diffraction(XRD). Photocatalytic degradation of crystal violet with Ag2S-Ag nanorods was under visible light irradiation. The experimental results show that within50min the degradation of20mL1×10-5crystal violet solution can almost reach100%. We study the variation on the concentration of crystal violet with reaction time, we supposed that the catalytic degradation of crystal violet may be a zero-order reaction. Then, SERS enhance performance of Ag2S-Ag nanorod was test by different concentrations of crystal violet as probe, the results showed that the intensity of SERS spectrum was rapidly reduce with the decrease of concentration of crystal violet and the signals enhancement is mainly caused by the charge transfer. Ag2S-Ag nanorods can detection the crystal violet as low as1×10-6M.(2) Cu2O octahedron nanoparticles were prepared by chemical precipitation in80℃water bath. CuO-Ag nanoparticles were synthesis by Cu2O reaction with Ag+. The products were characterized by scanning electron microscopy(SEM), UV-visible absorption spectroscopy(UV-Vis), X-ray powder diffraction(XRD). The organic molecules such as Crystal violet, methylene blue, rhodamine6G were act as probes to study the SERS activity of CuO-Ag. CuO-Ag nanoparticles can detect10-7M methylene blue and enhancement factor is6.6×105.