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-Fe
3
O
4
hetero-dimer nanoparticles (NPs) with enhanced magneto-optical properties via a thermal decomposition route. Employing triiron dodecacarbonyl (Fe
3
(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 Fe
3
(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 Fe
3
O
4
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-Fe
3
O
4
NPs highlights their significant potential for magnetic-plasmonic bio-applications.