Efficient Synthesis and Magneto-Optical Enhancement of Au-Fe3O4 Hetero-dimer Nanoparticles with Triiron Dodecacarbonyl

This study presents a pioneering and efficient method for synthesizing Au-Fe3O4 hetero-dimer nanoparticles (NPs) with enhanced magneto-optical properties via a thermal decomposition route. Employing triiron dodecacarbonyl (Fe3(CO)12) as a safer alternative to the commonly used toxic iron pentacarbonyl (Fe(CO)5), we achieved a near 100% production yield by optimizing the molar ratio of Au seeds to Fe3(CO)12 (0.6:2.0 mmol) and reflux time (60 min). The resulting hetero-dimer NPs, featuring an Au component of medium diameter $\boldsymbol{d}_{\mathbf{0}}=\mathbf{6.89}$ nm and a Fe3O4 component of $\boldsymbol{d}_{\mathbf{0}}=\mathbf{14.51}\ \mathbf{nm}$ (with $\boldsymbol{d}_{\mathbf{0}}=\mathbf{4.22}$ nm Au seeds used), exhibited remarkable magneto-optical properties. These included a high magnetization ($\boldsymbol{M}\mathbf{s}=\mathbf{72.6}\ \mathbf{emu} /\mathbf{g}-\mathbf{Fe}\mathbf{3}\mathbf{O}_{\mathbf{4}}$ at 300K) and a well-defined plasmon resonance band at 553 nm, showcasing a 42 nm red shift from that observed in pure Au NPs. The use of triiron dodecacarbonyl as a precursor in the synthesis of these high-quality Au-Fe3O4 NPs highlights their significant potential for magnetic-plasmonic bio-applications.