Synthesis & Characterization Of Nano/Micro Structures Of Copper And Its Oxides

It is well known that the size, morphology and structure of materials significantly influence their physical and chemical properties and therefore their applications. Synthesizing nano/ micro-materials with specific morphologies or structures has attracted increasing attention nowdays. Extensive studies have been devoted to the controlled synthesis of nano/ micro-materials with various morphology and structure in the past few decades. In this paper, we synthesized nano/ micro-materials of copper and its oxides with diverse morphologies and structures using different methods and controlled their morphologies by varying experimental parameters. The growth mechanisms of these nano/ micro-materials are also discussed.1. Cu/Cu₂O composite mesoporous nanospheres with diameters of 150-200 nm were synthesized by a simple solution process at 100 oC for 90 min using copper nitrate, NaOH, and hexamethylenetetramine （HMTA）, L-Ascorbic acid （Vc） and without any surfactants or templates. The morphological and structural investigations by field emission scanning electron microscope （FESEM） and transmission electron microscopy （TEM） revealed that the volume of pores increase with the increase of reaction time and temperature. The effects of HMTA, NaOH and reducing agent are also investigated. And based on the investigation, the possible growth mechanism for the formation of the mesoporous nanospheres was discussed.2. Cu₂O nanospheres with relative uniform diameters of ²00nm were obtained by a liquid-phase reducing process using HMTA as both reactant and dispersant and Vc as reducing agent. The morphology and microstructures of the products were studied by FESEM, TEM and X-ray diffractometer （XRD）. The effects of pH and reducing agent on the morphology of the products were investigated. The formation mechanism of the nanospheres was discussed.3. Instant noodle-like Cu₂O nanowires with diameters of 30nm to 100nm and lengths up to 1μm were obtained simultaneously along with Cu₂O microspheres with diameters of 200nm-5μm by a simple aqueous reduction process using copper nitrate, HMTA, NaOH and glucose at 100°C for 3h. The effects of reaction time and glucose concentration were investigated. The possible growth mechanism of the noodle-like Cu₂O nanowires was proposed.4. Cu₂O concave octahedron microcrystals with edges lengths of 5-10μm were synthesized by reducing Cu²⁺ with glucose in alkaline solution at 50 oC using cetyltriethylammnonium bromide （CTAB） as surfactant. The growth process of Cu₂O was studied by FESEM and TEM. The results indicated that Cu₂O concave octahedrons were formed by shape evolution of smaller regular octahedron as the edge lengths and concavity increased with time. It is also found that the reaction temperature has significant effect on the formation of Cu₂O concave octahedrons. Finally the formation mechanism of the concave octahedrons was explained. 5. Copper nanowires with high aspect ratios were synthesized by solventhermal reduction of Cu²⁺ in H₂O/CTAB/n-butanol/n-hexane reverse microemulsion system. The effects of water to surfactant molar ratio （ω）, reaction time, reaction temperature and microemlsion were investigated. The formation mechanism of the nanowires was discussed.