Aerosol-assisted synthesis of gold nanoparticles

Gold nanoparticles (AuNPs) were prepared with the atmospheric-pressure aerosol-assisted synthesis at temperatures between 200 and 800 °C. A designed, air-stable homoleptic cluster (AuC2R)10 (R = 2,6-dimethyl-4-heptanol) was used as the precursor. In this process, the aerosol droplets acted like microreactors in which the AuNPs were formed within few seconds. A dramatic change of color from bright yellow to very dark red of the produced particles took place as the temperature increased. In addition, a clear transformation from droplet-like, spherical gold particle clusters to solid, irregular nanoclusters took place as temperature increased from 200 to 800 °C. A systematic investigation of the influence of the process conditions (e.g., solvent, temperature) on the powder characteristics, including the particle size, crystallinity, structure, and surface morphology, was carried out. The primary particle size was below 5 nm in all cases and no significant sintering took place even with the particles prepared at high temperatures. Furthermore, the produced gold nanoparticles were phase pure with crystallite sizes between 1.8 and 2.8 nm depending on the process conditions. A formation of large number of monodisperse, non-sintered Au nanoparticles from one single droplet in spray synthesis has not been reported before.