On Multi-morphologically Controlled Syntheses Of Gold Nanoparticles Under Systems With Aldehyde Groups And Mechanism Discussions

Gold nanoparticles have received a great deal of attentions due to their special optical and electrical performances, catalytic properties and remarkable quantum size effect, surface effect etc. Since these special properties are highly dependent on their morphology and size, to efficiently utilize gold nanoparticles in the future, it’s the vast concern in this field to realize the shape-controlled syntheses of gold nanoparticles with chemosynthesis.The recent decades saw many publications about shape-controlled syntheses of gold nanoparticles using different chemical systems, amongst which, polyvinylpyrrolidone(PVP) has been always used as capping agent to direct crystal growth of gold nanoparticles. However, to our knowledge, there are few researches on the fundamental function of PVP monomer, namely N-VinyPyrrolidone(NVP). Theoretically speaking, oxygen and nitrogen in NVP molecule can be strongly selectively and chemically adsorbed on different crystal faces of gold nanoparticles to direct anisotropic growth or to stop those to certain directions to form steady and golden nanoparticles of special shapes. On this cognition, this thesis experimentally analyzes and addresses the influence of N-VinyPyrrolidone on shape-controlled syntheses of gold nanoparticles.During study, N-VinyPyrrolidone is found to not only, as reducing agents and stabilizer, produce stable gold nanoparticles, but also direct gold nanoparticles to grow into usual hexagon and triangle nanoplates. Then the influences are investigated of different reaction conditions of this system. Finally, with the help of characterization methods including Fourier Transform Infrared Spectroscopy, Transmission Electron Microscopy, Scanning Electron Microscope, X-Ray Diffraction, confirmatory discussion and analyses are addressed on reaction processes and growth mechanisms of gold nanoplates.On researching N-VinyPyrrolidone, it is also found that it is acetaldehyde, produced by hydrolysis of this chemical, that acts as reducing agent for gold salt precursor. Inspired by this, we tried to apply acetaldehyde to produce nanoparticles directly. When PVP as capping agent are introduced to acetaldehyde system, a hitherto unknown shape of gold nanoparticles, nanohexagram, are synthesized. Then according to characterization data of gold nanohexagram, we propose a novel mechanism model to reveal growth mechanism of this original morphology.