Silica-coating of metallic copper nanoparticles in aqueous solution

This paper describes a method for silica-coating of metallic Cu nanoparticles in aqueous solution. Colloid solution of Cu nanoparticles was prepared from CuCl2 (0.001 M), a reducing reagent, hydrazine (0.1 M), and stabilizers, citric acid (0.005 M) and cetyltrimethylammonium bromide (0.0005 M), in water in air. The silica-coating was performed in aqueous solution with a silane coupling agent, (3-aminopropyl)trimethoxysilane (0.0001 M), and a silica source, sodium silicate solution (0.144 M), in the presence of the Cu nanoparticle colloid. UV–vis absorption measurements, TEM observation and X-ray diffraction measurements revealed that the metallic Cu nanoparticles with a size of 51.2 ± 23.6 nm were coated with silica.