Preparation,Characterization And Catalytic Performance Of Cu Nanowires And Their Related Structure

Copper nanowires, due to its high aspect ratio and large spectific surface area, can exhibit excellent properties and promising applications such as electronics and catalysis. Recently, domestic and foreign researchers carried out some exploratory work on the preparation,1properties and application of Cu nanowires.In this work, we studied the growth of Cu nanowires via solution reduction method in the presence of different linear alkyl diamines. then we prepared Cu with hierarchical structure by using capping agent which can lead the oriented growth of Cu and stirring-induced aggregation. At last, we replaced Cu(NO3)2by Cu(OH)2that can reused waste water, meanwhile the uniform and thin copper nanowires were prepared, then Cu nanowires catalyzing hydrogenation activity and selectivity of cinnamaldehyde(CMA) were studied. The main conclusions are drawn from this work as follows:In the cupric nitrate-diamine-hydrazine system, the morphology of Cu is varies with the type and concentration of diamine. Long nanowires are found to be easily formed in the diamines with short carbon chain length, such as ethylenediamine(EDA) and1,3-propanediamine (PDA). For1.4-butanediamine(BDA), the nanowires become shorter, while1.6-hexylendiamine is used, the product is in the form of nanoparticle ultimately. The presence of EDA or PDA of high concentration favors the formation of Cu nanoparticles, while the rise in BDA amount can change the surface feature of Cu nanowires, namely from groove-structured surface to smooth surface.The morphology of Cu does not change with the change of the concentration of HDA. An analysis of corrlation of the reduction process of Cu(Ⅱ) to Cu with the diamine-dependent morphology reveals that the role of diamines in the growth of Cu nanowires is twofold:(i) complexation with Cu+to dissolve the insoluble Cu(Ⅰ) intermediate, allowing homogeneous nucleation and growth of Cu crystals at a low rate,(ii) selective adsorption on Cu surface to achieve an orientated growth of Cu crystalas. The results also show that many single-crystalline nanowires can simultaneously grow from a polycrystal-line Cu seed.The oriented growth of Cu nanowires can be significantly disturbed by vigorous stirring, resulting in large-scale growth of Cu dendritic crystals, we have also analyzed the components, structures and morphologies of the producte synthesized under different type of diamines, diamine concentration, stirring rate and stirring time, and herein we believed that mechanism of these Cu hierarchical structure has the experienced necessary three stage, namely formation of crystal nucleus and growth of Cu small-sized nanocrystals which aggregate into large-sized polycrystalline particles, formation of bumps and then cusps, growth along both axial and radial directions. Growing into basic units which in the end have created complicated hierarchical structures.By replacing the Cu source (namely Cu(NO3)2) with Cu(OH)2) and recycling the produced wastewater. We appropriately controlling the amount of ethylenediamine(0.3mL)and hydrazine(0.08mL) added in the synthesis of Cu nanowires in the case of reusing the wastewater, we found it that the morphology of Cu nanowires are almost kept unchanged even though the wastewater is recycled more than ten times. The endlessly reusable wastewater resulting from the replacement of normally-used Cu(NO3)2with Cu(OH)2not only significantly reduce the cost of Cu nanowires but also make this approach environmentally friendly, then we used copper nanowires catalyzing hydrogention CMA. By comparing Cu nanowires with Cu nanoparticles, we found that the catalytic activity of copper nanowires increased by nearly30%compared to Cu nanoparticles.