Preparation Of Silver/Silica Core/Shell Composite Nanoparticles And Its Marine Anticorrosion Property

In recent years, considerable effort has been devoted to the design and controlled fabrication of core-shell nanoparticles with their unique optical, electrical, photocatalytic and chemical properties. However, most procedures described so far yield stable monodisperse Ag-SiO2core-shell nanoparticles only at relatively low concentrations and the reaction process was complex, therefore, are not suitable for large-scale synthesis and applications. In this paper, the preparation procedure of monodispersed Ag-SiO2core-shell nanoparticles was studied. Silver/silica core-shell nanoparticles were proposed as new antifouling coating additive, and it may be reasonably presumed that the new silver/silica coating additive can be both friendly to the environment and have long-lasting anticorrosion effective. TEM, UV-visible absorption spectroscopy, X-ray diffraction measurements and Zeta potential were applied for products characterizations and the electrochemical noise analyse was used for exploring the marine anticorrosion performance of Ag/SiO2core-shell nanoparticles. The main contents are as follows:1. Hydrazine hydrate was used as reducing agent and CTAB was selected as a protective agent. The as-prepared Ag/SiO2nanoparticles can be controlled by changing the reaction time and the concentration of CTAB, TEOS, ethanol and ammonia. We got the optimal reaction conditionsThe Ag core was10-18nm and the SiO2shell was18-30nm in diameter, the BET surface area was136.05m2/g.2. Highly concentrated monodisperse silver/silica nanoparticles were successfully prepared by adopting ascorbic acid as reducing agent, TEOS as silica precursor and sodium hydroxide as catalyst. The nanoparticles had a BET surface area of179.29m/g and a spherical silver core in a size range from14-26nm in diameter and an amorphous silica shell of15-28nm thickness, respectively. Ag crystal was never oxidized within the reaction due to the protection of silica. Such core-shell structure nanoparticles have displayed excellent antibacterial effects defending gram-positive and gram-negative bacteria even at a low concentration.3. To test the Ag/SiO2core/shell particles anticorrosion performance, the electrochemical noise analyse was used. The silver/silica core-shell nanoparticles were firstly dissolved in ethanol/acetone solution before being added to epoxy resin varnish. The accelerated tests were performed in fresh seawater with the addition of nutrient substances. The results showed that compared with the blank, the Ag/SiO2core/shell nanoparticles had an obvious effect in improving the anticorrosion ability of steal defending inorganic salts and microorganism corrosion in a long period. The inhibition efficiency of corrosion can reach as high as about99%.