Controlled synthesis of copper nano/microstructures using ascorbic acid in aqueous CTAB solution

Abstract

This paper describes a low-temperature green chemical synthesis of various morphologies of copper nano/microstructures. These syntheses achieved high yields in aqueous solution using ascorbic acid as a reductant and the cationic surfactant cetyltrimethylammonium bromide (CTAB) as a capping agent. The resulting copper particles were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and UV–Vis. absorption spectroscopy techniques. From the SEM analysis, it was found that different morphologies of copper particles, including submicron polyhedrons, micrometer rods, spherical nanoparticles, and nanowires were obtained by varying factors such as the molar ratio of reactants (ascorbic acid and CuSO 4·5H 2O), pH, reaction time, and temperature. Increasing the molar ratio of ascorbic acid to precursor salt and increasing the pH led to a decrease in the size of copper particles formed. At short reaction times, spherical copper nanoparticles with an average diameter of 90 nm are obtained. When the reaction time was prolonged, the nanoparticles transformed into nanowires with diameters in the range of 100–250 nm, and lengths of up to 6–8 μm. When the reaction temperature was decreased, Cu mixed with Cu 2O particles were obtained instead of Cu particles. The resultant copper particles were confirmed by EDX and XRD to be pure Cu, with face-centred cubic (fcc) structures.