Gram-Scale Green Synthesis of Copper Nanowire Powder for Nanofluid Applications

• Published in: ACS sustainable chemistry & engineering 2019-07, Vol.7 (14), p.12376-12388, Article acssuschemeng.9b01814
• Main Authors: Maji, Nitai C, Chakraborty, Jayanta
• Format: Article
• Language: English
• ISSN: 2168-0485; 2168-0485
• DOI: 10.1021/acssuschemeng.9b01814

Copper nanowire is a promising new filler for nanofluids for cooling applications. Elongated one-dimensional nanostructures such as nanowires provide a percolated network for fast conduction of heat in the low conducting fluid. In this study, copper nanowires have been synthesized in gram-scale via wet chemical reduction with ethylenediamine-mediated anisotropic growth. In similar existing protocols, around 2.4 kg of NaOH is discharged per gram of Cu nanowires, whereas, in the present method, unreacted reactants have been successfully recycled for subsequent batches after precise quantification by a combination of titration, spectroscopy, and chromatography. Such green synthesis (zero discharge) of copper nanowires in powder form has been reported for the first time. The improved method also reduces the cost of production substantially. Extensive characterization of the product has been carried out using field emission scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray diffraction analysis to ensure the quality of the material. The effect of different reaction conditions on product quality has also been studied. Finally, copper nanowire powder was dispersed in ethylene glycol to prepare nanofluids that show a significant enhancement (20%) in thermal conductivity at low loading (0.15 vol %).