Study on Synthesis of Conductive Copper Nanoparticles by Chemical Reduction Method

• Main Authors: Yu-Yu Lin, 林育右
• Other Authors: Huey-Ing Chen
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/82098432478358812048

碩士 === 國立成功大學 === 化學工程學系碩博士班 === 91 === In this work, Cu nanoparticles were obtained by the chemical reduction of copper sulfate with hydrazine at room temperature. Polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) were used as the protecting agents (PA). The influences of synthesis parameters, including copper sulfate concentration, [N2H4]/[Cu2+] ratio, [PA]/[Cu2+] ratio, solvent, atmosphere, temperature, and the addition of alkali on the resultant Cu nanoparticles were investigated. The shape, crystalline structure, particle size and particle size distribution of the as-prepared particles were characterized by TEM, XRD, HRAEM, and UV/Vis spectra analyses. The results showed that the f.c.c. structured Cu nanoparticles sized ranging from 3 to 80 nm can be obtained in the presence of PA. The particle size was decreased with increasing the CuSO4 concentration and the [PA]/[Cu2+] ratio. On the contrary, the particle size was increased with the increase of [N2H4]/[Cu2+] ratio and temperature. According to the analyses of IR and XAS, it was found that Cu nanoparticles can not be efficiently protected by PVA due to their weak interaction. However, the Strong interaction of Cu with PVP caused the decreasing in the particle size of Cu nanoparticles. In the case of ethanol/water as solvent, and with the presence of PVP, the resulting size (9nm) of Cu nanoparticles was obviously larger than that in the aqueous solution (4nm). This could be inferred that the presence of ethanol would weaken the interaction between PVP and Cu nanoparticles, which resulted in the increase of particle size. Whereas, the particle size (51nm) was smaller than that in the aqueous solution (109nm) in the absence of protecting agent. Furthermore, from the result of XRD analysis, trace CuO and Cu2O were found in the products at high [ethanol]/[H2O] ratio. When NH4OH and NaOH were used as the alkaline solutions, although the [N2H4]/[Cu2+] ratio could not be reduced, the Cu nanoparticles with size smaller than 15nm could be obtained without protecting agent. The Cu-core/Ag-shell nanoparticles had also been synthesized by successive chemical reduction method. The core-shell structure of the as-synthesized Cu/Ag nanoparticles could be confirmed by the UV/Vis absorption spectra. When the molar ratio of Cu/Ag was 1:4.83, the particle size of obtained Cu- core/Ag-shell nanoparticles was about 11nm, and that of Cu cores was about 5nm. Metal doped PVA films, including Cu-PVA, Ag-PVA, and Cu/Ag-PVA films, were used to measure the conductivity. The result showed that for Cu-PVA and Ag-PVA films, as the dosage of Cu nanoparticles was increased up to 0.2wt%, the conductivity was risen dramatically. Besides, the conductivity was increased with decreasing the particle size. However, the dosage of abrupt rise was about 0.1wt% for Cu/Ag-PVA film, which was smaller than that for others. This was probably because the Cu/Ag nanoparticles were relatively well-dispersed in the PVA films.