Synthesis And Growth Mechanism Of Cu Nanostructures Induced By Au Seeds

Copper(Cu)nanowires have attracted considerable interest because of the unique electrical,thermal and malleable properties,which have wide use in the applications,such as transparent electrodes and electronic devices.Especially,Cu is lower cost and higher abundance in the earth compared with noble metals.With the going deep of the research work,it was found that the optical and catalytic properties of copper nanostructures with different morphologies are similar to that of the noble metal nanostructures.In this dissertation,the syntheses of Cu nanorods,Cu nanocuboids and Cu nanopolyhedrons are explored,and First-principles calculations are also utilized to analyze the growth mechanism of Cu nanostructures.The main work and some results included in this dissertation are as follows:1.Cu nanorods are synthesized with Au nanobipyramids using seed-mediated method,and the effects of different experimental parameters are discussed.The length and morphology of Cu nanorods can be tuned by controlling the amount of seeds and precursor,respectively.Based on the First-principles calculations,it is indicated that Cu atoms prefer to deposit on the side face of seeds because of the higher bonding energy.Cu atoms are easy to occur the phenomenon of migration,and the competition between deposition rate and migration rate results in the formations of Cu nanorods with different morphologies.Under the circumstance of lower concentration of precursor,the deposited Cu atoms will migrate to the other end the Au nanobipyramids,which leads to the growth of Cu nanorods along one end of the seeds.Whereas in the case of higher concentration,the depostied Cu atoms without migration can create active sites on one end of Au nanobipyramids,which leads to the growth of Cu nanorods along two ends of seeds.2.The Cu nanocubiods are synthesized with Au nanorods using seed-mediated method.The size of the Cu nanocuboids can be controlled by adjusting the amount of Au nanorods.The deposition rate of Cu atoms on the sides is higher than that on the ends of Au nanorods.It is found that the Cu atoms deposited on seeds surface is island distribution instead of uniform anisotropic growth owing to the large lattice mismatch.As the further reaction,the truncated Cu structures gradually change into the rectangular Cu nanocubiods under the limitation of ODA.3.The Cu nanopolyhedrons are synthesized with Au nanospheres using seed-mediated method.The effects of experimental parameters,such as the reaction temperature,on the growth of the Cu nanopolyhedrons are investigated.Compared with the Cu nanostructures by self-nucleation,it is found that Cu atoms prefer to deposit on the seeds,and the crystal facets of seeds with different surface energy can significantly influence the deposition of Cu atoms.As it is known that the diffusion of Cu atoms between different crystal facets can be hindered by the energy barriers,resulting in the formation of irregular Cu nanopolyhedrons.At high temperture,the improved diffusion rate can result in the formation of Cu nanocubes.Moreover,FDTD simulations and optical measurement are used to explore the extinction spetra of Cu nanorods and Cu nanocubiods,and the disagreements between experimental and theoretical optical properties of the Cu nanostructures are analyzed.