Size-controlled synthesis of gold nanoparticles by a novel atmospheric pressure glow discharge system with a metallic pin electrode and a flowing liquid electrode

Abstract

A direct current atmospheric pressure glow discharge (APGD) operated between a pin-type solid metallic electrode and the surface of a flowing solution (the liquid electrode), positively or negatively charged and serving as the flowing liquid anode (FLA) or cathode (FLC), was used for synthesizing gold nanoparticles (AuNPs). To the best of our knowledge, the synthesis of AuNPs in such a system, with no noble gas required to support the APGD, has never been reported. The effect of the selected operating parameters on the performance of the AuNPs synthesis in the plasma-reaction system with the FLA or FLC was examined. The design of the experiments (DOE) was conducted using the response surface regression (RSR) approach. The response of both systems was the wavelength of the maximum (λ_max) of the localized surface plasmon resonance (LSPR) absorption band of the AuNPs. On the basis of the established full quadratic regression models, the optimal operating parameters for both plasma-reaction systems (with the FLA or the FLC) were selected, which allowed for the smallest in size spherical AuNPs to be obtained. Both regression models were validated, the AuNPs produced in both plasma-reaction systems under the optimal operating parameters were characterized by UV-Vis absorption spectrophotometry, scanning electron microscopy (SEM) and transmission electron microscopy (TEM).