Synthesis And Surface-Enhanced Raman Scattering Properties Of Nanocomposites Templated From Butterfly Wings

Materials have been always considered as key elements in human's lives, and which played important roles in the development of societies. With steps of the modernization, the research in highly technological fields, such as the aerospace research fields, requires materials with more satisfying properties. Meanwhile, when considering application aspects, we also need relatively lower fabrication costs with satisfying properties. It has been demonstrated by former research that other than chemical components, the structures of materials will also have significant influences on the properties of materials. The researches on designing materials with some special structures with satisfying properties have always been the aim of materials scientists. On the way of design materials with certain structures, nature provided us with thousands of examples and inspiration. Resulting from millennium of evolution, natural biological species often consist of structures with periodicity, hierarchical architecture and sophistications which endow them with adaptability to natural environment and some special functions for their daily lives. Humans should learn from nature to apply the advantages of natural structures in our lives. Materials scientists have long been focusing on fabricating the natural nanostructures, and applied them in novel materials for satisfying properties. These methods also enabled scientists to fabricate materials with lower costs and inspired ways of design novel materials.To our knowledge, in the past forty years, Surface-enhanced Raman Scattering (SERS), as an effective analytical tool, has been widely used many research fields, such as Chemistry, Life Science, and Materials Science, etc. With the development of SERS, the substrates have also been developed from former 3D nanostructures of noble metals, transition metals to semiconductors and nanocomposites. Especially, many research have already demonstrated that the noble metal nanoparticles (NPs) and Semiconductor NPs have synergetic contribution for the enhancement effect, thus, increasing number of work have been applied the nanocomposites in synthesize novel SERS substrates. However, traditional fabrication methods often requires high technologically facilities, which will increase the cost of SERS substrates. In order to improve SERS as a more efficient analytical tool, the requirements for substrates should be followings: high sensitivity, satisfying reproducibility and stability as well as lower cost. Butterfly wing scales consist of 3D nanostructures which directly related to the optical properties of butterfly wings. Inspired by natural nanostructures, we applied different butterfly wings as original templates to fabricate Biomorphic MeOx, and then incorporated Au and Ag NPs in this system to form nanocomposites as novel SERS substrates. Main research contents are as followings:1. Selected the fore wings of two kinds of butterfly: Papilio paris and Euploea mulciber as original templates to fabricate Biomorphic MeOx. In this work, the fabrication procedure mainly includes: precursor dipping and calcination. By using XRD, FESEM, TEM measurements, we characterized the crystal, morphologies, and detailed nanostructures'information of these metal oxides. From these results, we could confirm that these kinds of Biomorphic MeOx well conserved the morphologies of the original templates.2. By using the chlorauric acid as precursor, and treated the pre-dipped Biomorphic MeOx with calcination to 400oC to form Au-Biomorphic MeOx. XRD, XPS, FESEM, TEM results have shown the information of crystal, elemental, morphologies and scattering of nanoparticles. By choosing the Au-Biomorphic SnO₂(P) as representative materials to test its SERS spectra. By study the SERS spectra; we analyzed the advantages and disadvantages of this substrate. We also plan to select another template to synthesize the SERS substrates which will provide better reproducibility property.3. In order to get better reproducibility property of SERS spectra, we have selected another butterfly wing as templates. The fore wing scales of butterfly Euploea mulciber consist of 3D periodic photonic like nanostructures, which has already been studied by other former works. By using the similar synthesis methods as former work, we synthesized the Au-Biomorphic SnO₂(E) as SERS substrates. The SERS spectra were measured under same condition as former works. This substrate shows the better sensibility and much better reproducibility properties than the former work. By comparing the difference of the structural factors, we analyzed the enhancement mechanisms. This work offered us inspirations for biomimick design for novel SERS substrates by changing the morphologies of substrate and finding other original biological templates with different nanostructures for better SERS properties.