Sustainable route to bicomponent nanocomposites with plasmonic and magnetic properties

Many efforts have been devoted to elucidating the process-structure-function relationships in nanocomposites composed of noble metals (typically gold) and iron oxides (usually magnetite) due to their integrated plasmonic and magnetic properties. Chemical strategies for their preparation usually follow seed-mediated techniques where nucleation and growth of the magnetic iron oxide phase are promoted to occur on the surface of preformed gold nanoparticles, employing high-boiling organic solvents and organometallic iron precursors. Herein, an innovative environmentally friendly method for synthesizing noble metal-non stoichiometric magnetite nanocomposites in aqueous media is proposed. The approach relies on the partial oxidation of Fe(II) precursors using oxygen as an oxidizing agent in the presence of noble metal nanoparticles. The Fe(II) precursor concentration used in the synthetic process plays an important role in determining the structure of the obtained nanocomposites. The structure-dependent redshifts of the localized surface plasmon resonance were rationalized by applying a morphologically simple model to simulate their extinction spectra. In addition, the magnetic properties observed in the synthesized nanocomposites are in good agreement with previous reports. The approach proposed meets the current demands of sustainable development and advances the possibilities of synthesizing bicomponent nanocomposites with widespread scientific and technological relevance.