Study On The Preparation And The Performance Of Novel Porous SERS Substrates

Surface enhanced Raman scattering (SERS) has aroused wide concern and wide application prospect in the spectral material field for its high sensitivity and resolution. The development of novel multifunctional SERS substrate will solve the problem of SERS-active substrate shortage perfectly and increase applications. That is to say the progresses of SERS are strongly dependent on the development of the research and preparation of new SERS-active substrates. In fact, the fabrication of uniform and effective SERS substrate is still a challenging for high cost and complex synthetic process.In order to solve the above problems, porous flower-like HA/Ag nanocomposites was prepared via solvent-thermal method, porous and orderly Ni-doping TiO2 photonic crystal and Co-doping GO-TiO2 photonic crystals with inverse opal (IO) structure were also fabricated via bysol-gel method, respectively. The SERS and photoelectric performance were also discussed.The main achievements are summarized as follows:1. The porous flower-like HA/Ag nanocomposite was prepared via one-pot solvent-thermal method and was characterized by XRD patterns, SEM images, Raman specrta, etc. The results show that the Ag nanoparticles with uniform size were attached on the surface of porous flower hydroxyapatitean particles and could be used SERS-active substrates. The unique Raman enhancement effect of HA/Ag nanocomposites indicates that rhodamine 6G (Rh6G) can be detected at a concentration as low as 1×10-10 M. In addition, the surprise thing is that the as-prepared composite can greatly shorten the nitro phenol (4-NP) reduction time to 8 min. This synthetic method provides a reference for the preparation of other nanocomposites.2. The good-sized polystyrene sphere (PS) was served as a kind of template, to prepare the inverse opal structural Ni-doped TiO2 (Ni-TiO2) photonic crystal. The Ni-TiO2 acted as a SERS-active substrate. The study found that energy levels can be formed by the conduction band bottom in the energy gap of TiO2 by an appropriate amount Ni-doping, promote the HO2-to-molecule charge transfer process, and subsequently enhance SERS signals of 4-MBA molecules on Co-TiO2 substrates. The nanocomposites were used as SERS nanosensors to detect trace amounts of 4-MBA (1×10-11 M) and exhibit strong Raman activities. In addition, the samples show excellent photocatalytic activity for MB, the photocatalytic efficiency is 95% at an irradiation of 90 min under simulated sunlight irradiation.3. The inverse opal structural Co-doping GO-TiO2 photonic crystal was synthesized and served as SERS-active substrates. The improvement of SERS properties of the as-prepared substrates by Co doping and GO was mostly investigated. The results indicate that energy levels can be formed near by the conduction band bottom in the energy gap of TiO2 by an appropriate amount Co ions doping, which can promote the TiO2-to-molecule charge transfer process, and subsequently enhance SERS signals of 4-MBA molecules on Co-doping GO-TiO2 substrates, and improve SERS properties of TiO2 nanoparticles remarkably.4-MBA with the as-prepared substrates can be detected at a concentration as low as 1×1012 M. It is note that the photocurrent density and photocatalytic efficiency are enhanced by 1.5 times and 6 times through Co-doping GO-TiO2 photonic crystal to that of a TiO2 photonic crystal.