Preparation Of MnO / Au Composite Nanostructures And Their Surface Enhanced Raman Scattering Properties

Surface-enhanced Raman scattering (SERS) technology has been investigated for more than forty years since it was discovered in 1974. Nowadays, it has been widely applied to many fields, such as physics, chemistry, biology, archaeology, food hygiene and medicine. One of the fundamental issues for SERS applications routine detection work is the fabrication of SERS substrate with excellent sensitivity, good stability, and high reproducibility. Therefore, the fabrication of robust SERS substrate is a hot research subject in recent years. Among various SERS substrates, the substrates constructed by semiconductor nanostructures have shown excellent performance. In particular, the metal oxide nanostructures that can be prepared in simple and low-cost method have drawn much attention. The rapid development in chemical synthesis of various semiconductor nanostructures has stimulated the research in SERS field. Meanwhile, the studies on SERS technology also promote the development of novel semiconductor nanostructures.In this thesis, we report the preparation and application of a novel SERS substrate based on MnO2/Au hybrid nanowall film. The substrate was prepared by a simple and cheap hydrothermal method combined with subsequent vacuum thermal coating of Au nanoparticles. Detailed characterizations of MnO2 nanowall film and MnO2/Au hybrid nanowall film have been conducted with scanning electron microscope, transmission electron microscope, X-Ray powder diffraction, and so on. Enhanced SERS signal with increased thickness of gold layer was observed and a significant increase of enhancement factor up to 8 orders of magnitude was achieved. Finite-difference time-domain (FDTD) simulations have been carried out to elucidate the origin of the enhancement and the distribution of the "hot spots". Finally, the Raman mapping technology has been adopting to evaluate the reproducibility of the SERS substrate. A series of experimental evidences suggest that the as-prepared substrate possesses excellent SERS sensitivity, good stability and high reproducibility. Our results provide a novel MnO2/Au hybrid nanowall film as a convenient, cheap and robust SERS-active substrate for detecting biomolecules.