Synthesis of Cu nanoparticles by chemical reduction method
(1. Instituto de Investigación en Metalurgia y Materiales, UMSNH, Morelia Michoacán, 58000, Mexico;
2. Centro de Física Aplicada y Tecnología Avanzada, UNAM, Santiago de Querétaro, 76230, Mexico)
2. Centro de Física Aplicada y Tecnología Avanzada, UNAM, Santiago de Querétaro, 76230, Mexico)
Abstract: Cu nanoparticles (CuNPs) have been synthesized through an easy route by chemical reduction at room temperature. The Cu2+ ions were reduced and stabilized with sodium borohydride and polyvinylpyrrolidone, respectively. The effect of the variation of the reducing agent/precursor-salt (RA/PS) ratio on the size and morphology of the CuNPs was evaluated. The synthesized material was studied by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The UV-Vis spectra showed a CuNPs plasmon peak at 569 nm and another peak belonging to Cu2O at 485 nm. XRD analysis showed the fcc-Cu phase with a small amount of fcc-Cu2O compound. SEM and TEM studies displayed that small semispherical CuNPs of approximately 7 nm were obtained at the RA/PS ratio of 2.6. The excess of polyvinylpyrrolidone stabilizer played an essential role in preventing CuNPs oxidation. On the other side, Cu2O polyhedral particles with larger sizes up to 150 nm were identified in the RA/PS ratio range of 2.0-1.84. In addition, Cu2O particles having star morphologies with quantum confinement at their tips were obtained at the RA/PS ratio of 1.66.
Key words: Cu nanoparticles; NaBH4; chemical reduction; polyvinylpyrrolidone stabilization; Cu2O