Research On Controllable Synthesis And Optical Properties Of Copper Nanostructures

Copper(Cu)nanostructures possess excellent electrical,thermal and malleable properties for various applications,such as transparent electrodes,solar cells,and catalysis.Besides,Cu is lower cost and higher abundance in the earth.This dissertation bases on experimental and theoretical analysis on the synthesis and optical properties of the Cu nanowires,Cu nanocubes and Cu nanotetrahedrons.Finite-difference time-domain(FDTD)calculations are also ultilized to explore the absorbance and scattering characteristic of the as-prepared Cu nanocubes and Cu nanotetrahedrons.The results lay the foundation for the Cu nanostructures-based research and applications.The main work and some results included in this dissertation are as follows:1.Five-fold twinned Cu nanowires with uniform diameter are synthesized by a simple hydrothermal method.The effects of different experiment parameters,such as the temperature of solventthermal reaction,the concentration of reducing agents,and the kinds of capping agents,on the growth of the Cu nanowires are investigated.The growth mechanism of the obtained Cu nanowires was revealed by the UV-Vis spectra of the Cu2+-amine complexes with the presence of hexadecylamine(HDA)or octadecylamine(ODA).The final results show that Cu2+ can firstly form Cu2+-amine complexes with alkyl amine,and then the complexes are reduced to Cu0 under the condition of high temperature and pressure.When the temperature of solventthermal reaction or the concentration of reductant was increased,the reaction rate accelerated remarkably,which led to the fast nucleation of nanocrystals and further formation of the pentagonal bipyramids or pencil shaped nanocrystals.In addition,Cu nanowires can also be fabricated by modulating the types of alkyl amine from HDA to ODA or oleylamine(OLA),but the diameter of the nanowires was increased.2.An alkyl amine-mediated hydrothermal synthesis method is proposed for success fabrication of Cu nanotetrahedrons and nanocubes with controllable size.By increasing the complexation reaction temperature or modulating the type and ratio of the coordination chemistry(a sole ligand or dual ligands),Cu nanocrystals with different morphology and structures were obtained.Furthermore,according to the kinetics and thermodynamics,we explain the growth mechanism of Cu nanotetrahedrons and nanocubes.The results show that we can manipulate the concentration of Cu2+-amine complexes by changing the complexation reaction temperature,which effectively controlls the final morphology of nanostructures.The size of the nanopolyhedrons increases from 100 to 600 nm with decreasing the mole ratio of dual ligands(HDA to ODA).Importantly,this work proposed the fabrication method of Cu nanotetrahedrons at the first time.Therefore,the results will lay an important foundation for the Cu nanotetrahedrons-based research on the theory and experiment.3.FDTD simulations are used to explore the absorbance and scattering characteristic of the as-prepared Cu nanotetrahedrons and nanocubes.On this condition,the UV-Vis absorption and scattering spectra recorded from aqueous suspensions and solid powder of the Cu nanopolyhedrons are further discussed.The experiments pectroscopies are the superposition of the absorption spectra of nanocubes and nanotetrahedrons with different proportions.The peak at about 600 nm in the experimental spectra mainly originates from Cu nanocubes,and the absorption from 750 to 950 nm is derived from the Cu nanotetrahedrons.