3D Ag/ZnO Hybrids For Sensitive Surface-Enhanced Raman Scattering Detection

Surface-enhanced Raman scattering (SERS) spectroscopy provides an attractive tool with advantages of high specificity and sensitivity, simple sample pretreatment and rapid analysis time, its applications in the fields of physics, chemistry, biology, medicine attract a great deal of attention. In recent years, the scientists focus on the preparation of SERS substrates, besides the commonly used metal substrates, semiconductor-metal nanocomposites draw more attentions as SERS substrates because of the more flexible and stable structure and better SERS effect, due to both electromagnitism and chemical enhancement. In this study, To combine the surface plasma resonance of metal and local field enhancement in metal/semiconductor interface, Ag nanoparticles (NPs) were assembled on a ZnO nanorod array which was grown by hydrothermally on carbon fibers. The construction of dimensional (3D) Surface-Enhanced Raman Scattering (SERS) substrate is used for the sensitive detection of organic pollutants with the advantages such as facile synthesis, short detection time and low cost. The hybrid substrate was manifested a high sensitivity to phenol red at a lower concentration of 1×lO-9M and a higher enhancement factor of 3.18×109. Moreover, the ZnO nanostructures decorated with Ag NPs were demonstrated self-cleaning function under UV irradiation via photocatalytic degradation of the analytic molecules. The fabrication process of the materials and sensors, optimization of the SERS behaviors for different sized Ag NPs, the mechanism of SERS and recovery were presented with a detailed discussion. The main results and conclusions are summarized as follows:1. Firstly, the carbon fibers were washed repeatedly with acetone. Then a thin layer of ZnO was coated on carbon fibers by magnetron sputtering as a seed layer followed by hydrothermally growing of ZnO nanorods. Ag nanoparticles were adsorbed by electrostatic interaction in-situ. With adjustment of the size of Ag NPs, a high sensitive SERS substrate is synthesis.2. To understand the contribution to the enhancement of each component in the 3D SERS substrate, PATP was employed as probe molecules to investigate the SERS enhancing factor of the substrates. The limit of detection is 1×10-9M and the enhancement factor of 3×109. The result shows that the Raman signal of the PATP from the Ag NPs decorated ZnO-NRs/cfs substrates is much higher than pure Ag substrate and ZnO substrate, both electromagnetic and chemical mechanism are contributed to the enhancement of SERS.3. With red phenol was employed as probe molecules, the properties of this hybrid substrate is detected. It manifested a high sensitivity to phenol red at a low concentration of 1×10-9M and a high enhancement factor of 3.18x109 and the intensity of Raman signal varies with the concentration of the probe molecules into linear change. The Ag/ZnO hybrids also exhibited good photocatalytic activities of the adsorbed target molecules under UV irradiation. This structure enables promising applications in sensors for organic pollutant detection.