A partial oxidation-based approach to the synthesis of gold-magnetite hybrid nanostructures

Hybrid nanostructures composed of gold and magnetite are of singular interest because they allow the integration of plasmonic and magnetic properties in a single object. Due to this feature, their application has been proposed to perform various functions. The methods usually employed to prepare these particular kinds of nanostructures follow organic phase routes, whereas synthetic methodologies that employ more sustainable solvents have been much less explored. In this work, an environmentally friendly approach for the synthesis of gold-magnetite hybrid nanostructures in aqueous media is proposed. This approach relies on the partial oxidation of the Fe(II) precursor using hydrogen peroxide as the oxidizing agent in the presence of preformed gold nanoparticles dispersed in the reaction medium. The methodology used led to the formation of magnetite nanoparticles with a good stoichiometry and a median size of 30 nm. Furthermore, in the presence of gold nanoparticles in the reaction medium, the formation of gold-magnetite hybrid nanostructures is produced as a consequence of the heterogeneous nucleation of the iron oxide phase on the surface of the gold nanoparticles that act as seeds. The approach reported broadens the possibility of synthesizing hybrid nanostructures in aqueous media with integrated plasmonic and magnetic properties.