Crystal engineering and SERS properties of Ag-Fe3O4 nanohybrids: from heterodimer to core-shell nanostructures

Structure tailoring of hybrid nanoparticles is highly desirable for a number of applications, due to their controllable physical properties. Here, a family of Ag-Fe3O4 nanohybrids is synthesized via a simple one-step reaction of silver acetate and iron acetylacetonate in the presence of 1,2-dodecanediol, oleylamine and oleic acid. The as-obtained Ag-Fe3O4 nanohybrid could be finely tuned from heterodimer nanoparticles to flower-like or core-shell nanoparticles, by controlling the experimental conditions. The structural differences between these nanohybrids greatly affect their optical properties. The intense surface plasmon resonance (SPR) peak allows the heterodimer nanoparticles to act as a superior surface-enhanced Raman scattering (SERS) substrate, which has been demonstrated by using 2-naphthalenethiol as a probe molecule. It is noted that the SERS signal of 2-naphthalenethiol on the heterodimer nanoparticles is much stronger than those on the core-shell nanohybrid and Ag nanoparticles alone, indicating its potential in the fields of ultrasensitive detection and biological imaging.