Eco-friendly (green) synthesis of magnetically active gold nanoclusters

Abstract

Au–Fe_xO_y composite nanoparticles (NPs) are of great technological interest due to their combined optical and magnetic properties. However, typical syntheses are neither simple nor ecologically friendly, creating a challenging situation for process scale-up. Here we describe conditions for preparing Au–Fe_xO_y NPs in aqueous solutions and at ambient temperatures, without resorting to solvents or amphiphilic surfactants with poor sustainability profiles. These magnetic gold nanoclusters (MGNCs) are prepared in practical yields with average sizes slightly below 100 nm, and surface plasmon resonances that extend to near-infrared wavelengths, and sufficient magnetic moment (up to 6 emu g^–1) to permit collection within minutes by handheld magnets. The MGNCs also produce significant photoluminescence when excited at 488 nm. Energy dispersive X-ray (EDX) analysis indicates a relatively even distribution of Fe within the MGNCs, as opposed to a central magnetic core.

Keywords:

• Gold nanoparticles
• magnetic properties
• synthesis
• composite materials
• plasmon resonance
• luminescence
• sustainability

Classification:

• 40 Optical
• magnetic and electronic device materials
• 102 Porous / Nanoporous / Nanostructured materials
• 103 Composites
• 106 Metallic materials
• 203 Magnetics / Spintronics / Superconductors
• 204 Optics / Optical applications
• 301 Chemical syntheses / processing
• 308 Materials resources / recycling
• 501 Chemical analyses
• 503 TEM, STEM, SEM