Near-Field Enhancement Contribution to the Photoactivity in Magnetite-Gold Hybrid Nanostructures

Abstract

Hybrid nanostructures composed of magnetic iron oxides and plasmonic metals can convert light energy into chemical energy, and they can be easily manipulated through magnetic fields. As a consequence of these multifunctional features, they can be employed as magnetically recyclable heterogeneous photocatalysts. Herein, we report a two-step method for the preparation of magnetite (Fe3O4)-gold (Au) hybrid nanostructures in aqueous media. The obtained material resembles a core-satellite morphology of 60 nm Fe3O4 nanoparticles surrounded by nearly 20 nm spherical Au nanoparticles attached to their surface. The synthesized hybrid material exhibits enhanced capabilities for methylene blue photodegradation compared with bare Fe3O4 nanoparticles. Detailed electrodynamics simulations were performed to achieve further insight into the improved photoactive properties of the Fe3O4-Au hybrid nanostructures. The theoretical results show that the excitation of localized surface plasmon resonances in the Au component leads to greater light absorption in the Fe3O4 component, which ultimately impacts the improved photocatalytic properties of the hybrid nanostructure. Overall, this work provides a complementary approach toward a complete understanding of the enhanced photoactive properties of hybrid nanostructures and highlights the importance of considering their actual morphology into simulations.