Controllable Prepareration Of Silver And Copper Based Nanomaterials By Photochemical Reaction And Their Applications

Due to the unique surface plasmon resonances(SPRs), copper family metal(Au, Ag, Cu) nanomaterials exhibit excellent physical and chemical properties, especially the optical properties. SPRs is the important reason for plasmon-enhanced spectroscopy technologies, such as surface-enhanced Raman spectroscopy and plasmon-enhanced fluorescence spectroscopy. On the basis of plasmon-enhanced spectroscopy technologies, scientists have achieved trace detection, including the single-molecule detection. Besides, SPRs are also widely applicable in photocatalytic degradation, infrared hyperthermia, biomarker, etc.. With the help of various well-designed synthesis strategies, the properties of nanomaterials can be engineered through the controlling of their compositions, shapes, sizes, spatial dimensions, etc.. Current research’s interests mainly concentrate on gold and silver nanomaterials. On the contrary, silver oxide nanomaterials and copper based nanomaterials are investigated relatively few.Many synthetic strategies have been developed for the size-, shape-, and composition-controlled synthesising of nanomaterials, such as hydrothermal method, pulsed-laser deposition method, sol-gel method, electrochemical deposition method, chemical vapor deposition method and so on. Among the various reported synthetic strategies, the photochemical methods have many advantages including simple yet efficient, environment friendly, low-cost. In this research, we studied the photochemical synthesis of the following nanocrystals, including:(1) Hierachical superstructures of silver nanoparticles with morphology highly resembling multiple-growth-hillocks,(2) Ag/Ag2 O nanoplates, and(3) CuxOy nanoplates. The growth mechanisms were investigated. Further more, we have obtained the nanoporous Ag/Ag2 O nanoplates and nanoporous Cu O nanoplates through the solid-phase thermal decomposition of the photochemically synthesized Ag/Ag2 O nanoplates and CuxOy nanoplates respectively. The detailed results are described as following:1. First-time photochemical synthesis of hierarchical multiple-growth-hillocks superstructures of Ag nanoparticles: Specifically, the Ag+ ions adsorbed on Zn O surfaces were reduced by the photo-generated electrons under UV illumination, and the resulting Ag atoms furtherly grown into Ag nanoparticles. The mechanistic exploration suggested that driven by screw dislocations the in-situ photochemical synthesised Ag nanoparticles would further crystallize into the hierarchical multiple-growth-hillocks superstructures through the BCF(Burton-Cabrera-Frank) mechanism. That is, it is a screw dislocation-driven, nanoparticle-mediated crystallization process. We further demonstrated that the PL properties of Zn O film can be elegantly engineered by the hierarchical superstructures of Ag nanoparticles.2. Photochemical synthesis of Ag/Ag2 O nanoplates: The growth of Ag/Ag2 O nanoplates was driven by dual mechanisms: Firstly, the in-situ photochemical-synthesized Ag nanoparticles crystallize into small nanoplates upstanding on Zn O film. The nanoplates have rough surfaces and irregular edges through the layer-by-layer(LBL) mechanism; In the following, the small nanoplates are converted into large micro-sized nanoplates with smooth surfaces and smooth edges under UV illumination. Furthermore, nanopourous Ag/Ag2 O nanoplates were obtained through the solid-phase thermal decomposition of photochemical synthesized Ag/Ag2 O nanoplates, attributed to the partial decomposition of Ag2 O. Comparing to the Ag/Ag2 O nanoplates before thermal treatment, the nanoporous Ag/Ag2 O nanoplates exhibit much better SERS activity.3. Photochemical synthesis of CuxOy nanoplates: It was found that the growth mechanism of CuxOy nanoplates is similar to that of Ag/Ag2 O nanoplates. However, the growth rate of the CuxOy nanoplates is significantly faster than that of Ag/Ag2 O nanoplates under otherwise similar experimental conditions. The particular growth mechanism of CuxOy nanoplates is currently under investigation. Furthermore, nanoporous Cu O nanoplates were obtained through the solid-phase thermal decomposition of CuxOy nanoplates after enduring the annealing process under 350 ℃ which can find wide application in photocatalysis, sensing, etc.. The formation of nanoporosity is ascribed to the thermal decompositin of unstable copper oxides.