Synthesis of Variable-Sized Fe3O4 Nanocrystals by Visible Light Irradiation at Room Temperature

A rational new method for the synthesis of variable-sized Fe3O4 nanoparticles by aerial oxidation of Fe(OH)(2) under visible light irradiation in the presence of trace EDTA has been investigated. The size of the Fe3O4 nanocrystals was controlled at about 11.5-30.0 nm by varying the reaction conditions in aqueous solution at room temperature. The oxidation reaction was significantly accelerated by visible light in the presence of EDTA. A rapid oxidation rate was favorable for decreasing the size of the Fe3O4 nanocrystals. The as-obtained Fe3O4 particles showed uniform spherical shape and a narrow size distribution. The variable-sized Fe3O4 nanocrystals exhibited different magnetic properties.