The Preparation Of Micro-nano Composite Substrate And Its Application In Catalysis And Detection By SERS

Surface-enhanced Raman Scattering（SERS） is one of the effective technological means with characteristics of high sensitivity and high selectivity. There are two enhancement mechanism of SERS, electromagnetic enhancement mechanism and chemical enhancement mechanism. Whatever the enhancement mechanism is, the enhancement effect must take consideration of the function of substrates. The noble metals have been used to prepare for the traditional substrates. With the development of technology, different preparation method have been reported. It is interesting to the composite substrates from two different materials. In these works, we have composited two novel SERS substrates using different materials. These substrates can be used to catalysis and detection, and achieve excellent results. The major research contents as follows:a) 3D superhydrophobic SERS substrate for sensitive detection of pollutants in real environments.Polycyclic aromatic hydrocarbons（PAHs） are a series of organic pollutants that are slightly soluble or insoluble in water. They can not be detected with noble metals. However, the functionalized substrates can bring the superhydrophobic surface. The interaction of hydrophobic molecules make succeed with the detection of PAHs. The porous foam nickel as a medium, Au nanoparticles were evenly deposited on surface of nickel foam by galvanic replacement to form Au NPs/nickel foam. The as-prepared substrate was decorated with long-chain alkyl mercaptan molecules to obtain the 3D hydrophobic surface. The galvanic replacement time and decorated time were taken into account. When the detection of PAHs using 3D Au NPs/nickel foam, the pyrene concentrations as low as 10^-8 M, and the1-naphthol concentration is 10^-6 M. Au NPs/nickel foam can fabricate a system of oil-water separation. The modified 3D Au NPs/nickel foam can detect various kinds of PAHs and their derivatives.b) Facile Synthesis of Silver Nanoparticles/Carbon Dots for applications by SERS.Carbon dots（CDs） are novel carbon materials with a few nanometer size. CDs also exhibit the characteristics of low-toxicity, good biocompatibility. The composite of CDs and metal nanoparticles can form a new-type SERS substrate, Ag NPs/CDs. Amidation raction have been used to connect activated carboxylate radical of metal nanoparticles with amidogen of CDs. Ag NPs/CDs substrates can reduce evidently the fluorescence of CDs and keep the SERS enhancement effect. The D band and G band of carbon materials have been seen from the spectrum of CDs. The addition of CDs can influence the charge transfer between Ag NPs and PATP molecules. There is a charge competition of CDs-Ag NPs-PATP, and the effect of charge transfer at various power can be taken consideration. Ag NPs/CDs is a peroxidase-like, can catalyze TMB to TMB2+ with hydrogen peroxide. The concentration of hydrogen peroxide can be detected by using Ag NPs/CDs, and the minimum detectable concentration of hydrogen peroxide is 10^-8 M.