Nanocomposite layers synthesized by atmospheric-pressure plasma combined with an aerosolized gold salt solution: influence of the solution concentration

This work reports on an atmospheric-pressure plasma process that enables the deposition of organic/inorganic nanocomposite thin films in a single step, without direct handling of nanoparticles (NPs). The deposition strategy involves combining a planar dielectric barrier discharge (DBD) in N ₂ with an aerosol containing a gold salt (HAuCl ₄ ·3H ₂ O) dissolved in a polymerizable solvent (isopropanol). For this process, a dual-frequency power supply is used: the high frequency (HF) promotes the gold salt reduction, isopropanol plasma polymerization and matrix growth, while the low frequency (LF) enables the transport and deposition of NPs onto the substrate surface. Our previous study demonstrated that the ratio of HF duration to the whole cycle duration ( i.e. , the cumulated LF and HF durations) directly influences thin-film uniformity. Another key parameter in these aerosol-based processes is the concentration of gold precursor in solution. The present study specifically investigates how variations in gold concentration in the injected solution (0.1–0.6 wt.-% Au) affect the properties of the synthesized films. UV–Visible absorption spectroscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and scanning electron microscopy clearly show net differences in the optical, chemical, and morphological characteristics of the produced films, with those produced from lower gold concentrations exhibiting more uniform particle distribution and a less viscous nature.