Preparation and characterization of flower-like gold nanomaterials and iron oxide/gold composite nanomaterials

We have successfully synthesized flower-like gold nanomaterials and Fe ₃O₄/Au composite nanomaterials through the use of wet chemical methods in aqueous solution. In the presence of 0.5 mM citrate, 0.313 mM poly(ethylene glycol), and 109.72 mM sodium acetate (NaOAc), we prepared Au nanoflowers (NFs) having diameters ranging from 300 to 400 nm in aqueous solution after the reduction of Au ions at room temperature for 10 min. In the presence of spherical Fe₃O₄ nanomaterials, we applied a similar synthetic method to prepare Fe₃O₄/Au composite nanomaterials, including nanowires (NWs) that have a length of 1.58 μm and a width of 28.3 nm. We conducted energy-dispersive x-ray analysis, scanning electron microscopy, transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption, and x-ray powder diffraction measurements to characterize the as-prepared flower-like Au nanomaterials and Fe₃O₄/Au composite nanomaterials. From time-evolution TEM measurements, we suggested that Au atoms that were bound to the Fe₃O₄ nanomaterials grew to form Fe₃O₄/Au composite nanomaterials. The as-prepared Au NFs absorbed light strongly in the visible-near-infrared (Vis-NIR) region (500-1200 nm). The Fe₃O₄/Au composite nanomaterials had electronic conductivities greater than 100 nA at an applied voltage of 20 mV, which induced a temperature increase of 20.5 ± 0.5°C under an alternating magnetic field (62 μT).