Fabrication And Property Study Of Copper Nanomaterials

Owing to their outstanding performance in electrical conductivity, catalysis, and antisepsis, low price, and a wide range of promising applications, copper nanomaterials, including nanowires and nanoparticles, have attracted significant attention from both scientific and industrial communities. Exploration of convenient methods for their preparation, shape control and property tuning has become a research hot topic in recent years. Before this work, amine and carboxylic acid compounds have been found as effective capping agents to control the growth and morphology of Cu nanocrystals in their liquid phase chemical reduction preparation methods through the binding between amino or carboxylic units and Cu surface.However, there is no any report to use the compound containing both amino and carboxyl units as a capping agent. In this thesis work, amino acids, a family of biomolecules naturally bearing both amino and carboxyl functionalities, have been used as capping agents for Cu nanocrystal preparation for the first time. The corresponding liquid phase chemical reduction preparation methods and the properties of resulted Cu nanocrystals have been detailed investigated.It was found that the chemical structure of amino acids plays a primary role in the determination of Cu nanocrystal morphology. When amino acid side chains are alkyl or have another N-containing functionality, copper nanowires can be obtained.Otherwise, only copper nanoparticles are produced. Moreover, the size of side chains has been found to affect the morphology of copper nanomaterials, too. Bulky size tends to result in nanoparticles. Furthermore, X-ray photoelectron spectroscopy revealed that the binding mode of amino acid molecules on Cu surface is highly dependent on their chemical structures. When its side chain is alkyl or contains only hydroxyl unit, amino acid binds to Cu surface via both amino and carboxyl units.And the coordination between carboxyl unit and Cu is monodentate. In the cases of the side chains of amino acids contain another carboxyl unit, the binding is through the two carboxyl units in a bidentate coordination style, and without the participation of amino unit. When its side chain contains another amino, the amino acid binds to Cusurface via a bidentate-coordinated carboxyl unit and the amino unit in the side chain.These findings deepen the understanding of the interactions, including binding style and strength, between capping agent molecules and the surface of copper nanocrystals,and would are of theoretical significance.Furthermore, it was found that the produced copper nanocrystals exhibited excellent anti-oxidation and good aqueous dispersibility. The multiple functionalities of amino acids have been demonstrated to provide not only the strong binding units to Cu surface for morphology and growth control, but also free functional group, which improves the solvent dispersibility and offers possible active site for further modification.Based on these researches, it can be concluded that amino acids are a kind of excellent capping agents for the preparation of copper nanomaterials. Based on them,it is not only easy to realize the shape-controllable and diversified preparation of copper nanomaterials, but also greatly enhance the anti-oxidation and aqueous dispersibility. More than that, amino acids are inexpensive and nontoxic. Therefore,the preparation method for copper nanomaterials using amino acids as capping agents developed in this thesis, would have a promising industrial application potential.