Preparation and Characterization of Nanocomposite Thin Films Containing Gold Nanoparticles by a Single-Step Atmospheric Pressure Plasma Deposition Process

This study focuses on the plasma deposition of metal/polymer nanocomposite thin films at atmospheric pressure and low temperature. The synthesis process combines a dielectric barrier discharge (DBD) with the aerosol of a solution of a gold salt (i.e., tetrachloroauric acid trihydrate, HAuCl4·3H2O) in isopropanol. In particular, the solution is injected as an aerosol into a parallel-plate DBD fed with nitrogen and powered by a dual-frequency modulated (800 Hz/20 kHz) sinusoidal high voltage. The influence of the duty cycle (i.e., the ratio of high-frequency time to total cycle time) on the properties of the deposited layers is assessed, keeping constant the gold salt concentration in the aerosolized solution. The chemical composition, morphology, and optical properties of the deposited layers are determined using various characterization techniques, including attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, UV-Visible absorption spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectrometry. It appears that increasing the duty cycle affects both the growth rate of the nanocomposite thin film and the efficiency in gold salt reduction into metallic nanoparticles, thereby influencing the plasmonic properties. Overall, these results offer new insights into the potential of using a single-step aerosol-assisted plasma process to deposit functional organic/inorganic nanocomposite thin films at atmospheric pressure.