Copper Oxide Nanoparticles have great interest because their optical, catalytic, mechanical and electrical properties. Copper is a noble metal such as Au and Ag a good alternative material, because it is highly conductive and than they is much more economical. Copper plays due to its excellent electrical conductivity plays an important role in electronic circuits. Copper nanoparticles are cheap and their properties can be controlled according to the synthetic method. Further, in the catalyst, the nanoparticle has a higher efficiency than the particles. Copper nanoparticles are synthesized by different techniques. The most important for the synthesis of copper nanoparticles are chemical methods such as chemical reduction, electrochemical techniques, photochemical reduction and thermal decomposition. Copper nanoparticles can be easily oxidized to form copper oxide. To avoid oxidation, these methods are usually carried out in a non-aqueous medium in low precursor concentration, and under an inert atmosphere (argon, nitrogen).
One of the most important methods for the synthesis of copper nanoparticles is the reduction chemical method. In this technique a copper salt is reduced by a reducing agent such as polyols, sodium borohydride, Hydrazine, Ascorbic acid, hypophosphite . In addition, it is used from capping agents such as Polyethylene glycol and poly (vinylpyrrolidone) . Some of the chemical reducing reactions can be carried out at room temperature. Salzemann et al used microemulsion method to synthesize nanoparticles of copper with size of 3-13 nm. Copper nanoparticles were produced by the polyol method in ambient atmosphere. The obtained nanoparticles were confirmed by XRD to be crystalline copper. SEM study shows that sizes of particles produced were 48±8 nm. Colloidal copper with particle sizes of 40–80 nm has been reported from reduction with sodium borohydride in aqueous solution at room temperature. The copper nanoparticles were stabilized by starch. In 2008, copper nanoparticles were synthesized by the reduction of Cu2+ in solutions of poly(acrylic acid)-pluronic blends results in a stable sol of metallic copper with a particle size below 10 nm. Reduction of copper ions by sodium borohydride in the presence of sodium polyacrylate was reported. Copper nanocrystals sizes were 14 nm. Chatterjee et al. presented a simple method for synthesis of metallic copper nanoparticles using Cucl2 as reducing agent and gelatin as stabilizer with a size of 50-60 nm.
Chemical reduction method is one of the micro-emulsion technology. Microemulsion containing at least three components, i.e. polar phase (typically water), non-polar phase (usually oil) and surfactant isotropic, macroscopically homogeneous and thermodynamically stable solution. Copper nanoparticle synthesis by reducing the non-ionic oil in water used to NaBH 4 (W / O) microemulsion of aqueous cupric chloride solution to achieve. Solanki and so on. Microemulsion reported synthesis of copper and copper sulfide nanoparticles. X-ray diffraction analysis confirmed that nanoparticles of metallic copper present. In 2013, facile synthesis of copper and copper oxide nanoparticles size adjustable proposed by Kumar et al. They found that the reduction with hydrazine hydrate gives copper nanoparticles in an inert atmosphere of nitrogen, and under aerobic conditions the reaction of sodium borohydride, to give copper (II) oxide nanoparticles. In another study, the copper salt is dissolved in dioxane / -AOT solution and the hydrazine hydrate under vigorous stirring reduced. Nano colloid size of 70-80 nm.
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