| ABSTRACT |
The invention discloses a synthesis method for preparing magnetite/silica/silver/silver chloride coreshell nanostructure particles, by a simple, room temperature wet chemistry process. The coreshell nanostructure comprises of magnetite nanoparticle, which act as core and coated by an amorphous silica layer that act as a shell, forming the coreshell structure. The silver/silver chloride nanoparticles is formed/deposited on the surface of the silica-shell. The preparation method of the magnetite/silica/silver/silver chloride comprises the following steps: (1) Synthesis of magnetite nanoparticles by a reverse-coprecipitation of ion Fe2+ under ambient atmosphere. Ferrous sulfate is used as magnetite precursor while ammonium hydroxide is used as a precipitating agent. (2) The magnetite core nanoparticle is then coated by an amorphous silica layer by reaction of silica precursor, TEOS with ethanol, water and ammonium hydroxide. (3) The deposition of silver nanoparticles onto the silica surfaces is made by mixing the magnetite-silica solution with silver ions. The silver ions solution is prepared by mixing the silver nitrate powder with ammonium hydroxide solution. The positively charge silver ions will bond with the negatively charged hydroxyl group on the silica surface. Further reduction of silver ions into silver nanoparticles is made by reaction with polyvinylpyrrolidone (PVP), which act as reduction agent in alcohol solution. (4) The 50 nm average size of silver chloride (AgCl) nanoparticles with cubic structure is induced on the surface of silica-shell by the injection of hydrochloric acid (HCl) at a certain concentration into the magnetie-silica-silver ions solutions.
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