Novel Approach for the Electrosynthesis of Copper Nanoparticles

In recent decades, nanoparticles have become a prominent research topic due to their increased catalytic activity, which is attributed to their high surface areas. Although typical synthesis methods yield highly ordered monodispersed particles, they often require harsh synthesis conditions, such as high pressure or temperatures, and the use of high-purity reagents. Moreover, these syntheses are conducted on a microliter basis and are not easily scaled-up. 1 Electrochemistry offers an alternative approach for the synthesis of nanoparticles under mild conditions, since most metal reduction potentials occur at less than 2 V. One of the earliest attempts at the electrosynthesis of nanoparticles was conducted by Reetz et al. 2 In their work, a palladium sheet was stripped and then reduced ions at a platinum sheet to form nanoparticles. However, these nanoparticles were not monodispersed, and therefore not ideal for catalysis. In the present work, copper nanoparticles have been synthesized in bulk via oxidation of a copper wire into a 99.7:2.3 nitromethane-water solution in the presence of an acid. A copper wire was stripped into solution and monitored via chronocoulometry. Once oxidized, copper ions were stabilized with polyethylene glycol and diffused to the cathode where they underwent electrochemical reduction with the aid of a sonic probe, which dispersed uniform-sized nanoparticles into solution. The size of these nanospheres can be controlled to range from approximately 2 nm to 250 nm due to different amounts of surfactant and copper in solution. In addition, other nanoparticle shapes, namely nanospheres and nanocubes, were obtained when the acid was changed from perchloric acid to hydrochloric acid. These changes in composition of the electrolyte allow for control over the shape and size of nanoparticles. This new method for electrosynthesis of nanoparticles allows for their shape and size control, which can be useful for large-scale, industrial purposes. References Gawande, M.B., Goswami, A., Felpin, F., Asefa, T., Huang, X., Silva, R., Zou, X., Zboril, R., Varma, R. S., Cu and Cu-Based Nanoparticles: Synthesis and Applications in Catalysis. Rev. 2016 , 116 , 3722–3811. Reetz, M.T. , Helbig W., Size-Selective Synthesis of Nanostructured Transition Metal Clusters. Am. Chem. Soc. 1994 , 116 , 7401–7402.