Synthesis and surface plasmon resonance properties of carbon-coated Cu and Co nanoparticles

Carbon-coated Cu and Co nanoparticles were synthesized by the carbonization of PVA–metal hydroxide complexes. The possible reaction process and surface plasmon resonance (SPR) properties of the Cu and Co nanoparticles enwrapped in carbon layer were explored. The XRD results showed that no byproducts, such as oxides and carbides, were formed in the products, and the Cu and Co nanoparticles were effectively protected against oxidation by the carbon layer. The size ranges of the metal nanoparticles were 20–50 nm for Cu and 15–65 nm for Co, respectively. UV–vis absorption spectra showed that the SPR bands of the Cu and Co nanoparticles coated with carbon were red-shifted mainly due to the increase of the effective dielectric constant of the surrounding medium induced by the carbon layer.