Air stable colloidal copper nanoparticles: Synthesis, characterization and their surface-enhanced Raman scattering properties

• Air stable colloidal copper nanoparticles are synthesized by a simple chemical reduction method without any inert gas.
• The resulting nanoparticles were characterized by various spectroscopic techniques such as UV-visible, FT-IR, XRD and TEM.
• The copper nanoparticles do not suffer significant oxidation even after being stored for 6 months under ambient conditions.
• They exhibit large surface-enhanced Raman scattering (SERS) signals.

Air stable colloidal copper nanoparticles are synthesized by a simple chemical reduction method using octadecylsilane as a reducing agent and octadecylamine as a stabilizing agent in toluene without any inert gas. The formation of nanosized copper was confirmed by its characteristic surface plasmon absorption peaks in UV–visible spectra. The transmission electron microscopic (TEM) images show that the resulting copper nanoparticles are distributed uniformly with a narrow size distribution. The X-ray diffraction (XRD) demonstrated that the obtained copper nanoparticles are single crystalline nanoparticles. Fourier transform infra-red (FT-IR) spectroscopic data suggested that the silane Si–H is responsible for the reduction of copper ions. And also the resulting colloidal copper nanoparticles exhibit large surface-enhanced Raman scattering (SERS) signals.

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