Study of metal nanoparticles synthesized at the solid-liquid interface by atmospheric microplasma

• Main Authors: Yi-Wei Chiang, 姜翊惟
• Other Authors: Hong-Ren Jiang
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/agnmt6

碩士 === 國立臺灣大學 === 應用力學研究所 === 106 === Atmospheric-pressure plasma jet (APPJ) is not only used to treat the solid surface but also attracts great attention in the liquid phase. In particular, many studies report that the electrons could be provided continuously by APPJ to reduce the metal ions in the solution. Compared with the cathode of traditional electroplating, the cathode of APPJ is gas electrode. Hence, the metal crystals are nucleated in the solution. However, we observe that the nucleation site and the crystal shape would be changed in some condition (e.g. viscosity of the solution, additive, hydrophilicity of anode, etc.). The metal crystals are even nucleated on the anode. Based on these features, we propose a new technology which is directly writing metallic nanoparticles on the moist surface by APPJ. In the previous studies about the synthesis of metal nanoparticles by APPJ, most of them are the synthesis of metal nanoparticles in the solution and its application. It is rare to study the synthesis of metal nanoparticles on the solid surface and the nucleation site of metal nanoparticles, so this thesis is mainly divided into two parts. The first part is to study the effect of solution and surface properties on nucleation sites. In the second part, we prepare Janus particles on the moist surface by microplasma. In the first part of this paper, we use the laser marking machine to increase the hydrophilicity of Indium tin oxide (ITO) glass on which the silver nitrate solution was drop-coated. In this experiment, we observe that there are many Ag nanoparticles on the edge of the electrode. We also use the oxygen plasma to increase the hydrophilicity of the ITO glass and compare the difference between hydrophilic and hydrophobic nucleation at the same liquid level. Compare with the ITO glass without oxygen plasma treatment, the Ag nanoparticles are easily reduced on the hydrophilic ITO glass. In order to observe the influence of solution, we add glycerol and polyethylene glycol respectively to the solution to change the viscosity of the solution, in addition, we add the polystyrene particles to increase the nucleation site. The results show that the nucleation sites do change due to solution composition and even affect the crystal shapes. Based on the results of the first part, we apply this technique in the preparation of Ag nanoparticles coated Janus particles in the second part. The monolayer of PS particles is prepared on the agarose gel which contains the silver nitrate solution. Due to the mechanical properties and the thin water film of agarose gel, the indentation of agarose gel is caused by the surface tension of water film around the PS particles. When the atmospheric microplasma jet applied, the Ag nanoparticles will be reduced and attached to the lower hemisphere of PS particles. Based on the experiment results, we propose a new technology for preparing Ag nanoparticles coated Janus particles. This technology can adjust the particles size of Ag nanoparticles and the coverage of Janus particles. Moreover, the surface plasmon can also be observed, which makes the particles useful for the application of surface sensing and antibacterial function.