Gold nanoparticles synthesis by Microplasma-induced Non-equilibrium Liquid Chemistry (MiNE-LC)

The authors present a low-cost, rapid and environmentally friendly approach to synthesize gold nanoparticles (AuNPs) without any surfactants or stabilizing molecules. Aqueous solutions of Gold(III) chloride trihydrate (HAuCl4.3H2O) of different molar concentrations 0.2 mM, 1 mM and 5 mM were treated by microplasma with operating voltage of 1.1 kV and discharge current of 5.2 mA. Microplasma processed solutions were analysed by UV-Visible spectroscopy, TEM and Zeta sizer instrument. Gold precursor of lower molar concentration (0.2 mM) forms spherical, triangular and hexagonal AuNPs with diameters ranging from 20 nm to 60 nm and with a well-known red-purple colour when in colloidal dispersions. On the other hand, higher precursor concentrations 1 mM produces AuNPs with diameter above 100 nm exhibiting orange-coloured dispersions (1 mM) or network-like structures with large gold clusters (5 mM). 1